Sportsboard structures

ABSTRACT

A sports board that includes an elongate, water impervious, thermoplastic foam core having an upper surface and an under surface; an upper layer covering at least a portion of the upper surface; and an under layer covering at least a portion of the under surface. The foam core is made of a foamed material having a water absorption (measured according to ASTM C-272) of less than 2 volume percent.

REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. Provisional Application Ser. No. 60/920,073 filed Mar. 26, 2007 entitled “Sportsboard Structures,” which is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to novel sports boards that can be used for various sporting activities.

2. Description of the Prior Art

Boards and modified boards have been used for various sports and/or athletic activities such as for example surfing, riding waves, sail boarding, being towed by a boat, water skiing, snow boarding, sledding, snow skiing, and skate boarding.

Surfboards are flat or slightly curved narrow floating bodies which are suitable for use for one or more individuals to move along with or ride a swell or wave of water as it approaches land, a shoreline or a beach.

Sailboards can be similar to surfboards, but can be fitted with a sail, which catches available wind currents to propel the board, thus not relying solely on available water currents and/or waves to provide the impetus for forward motion.

Often, in order to stabilize the direction, surfboards and sailboards require a fin, i.e., a plate of triangular design, and whose plane is arranged essentially parallel to the plane of the direction of travel.

Surfboards and sailboards are generally made of wood, or a plastic material, for example, epoxy resin, acrylonitrile-butadiene-styrene (ABS) resin or similar materials, which form the actual rump or body and surround a core made of foamed material, such as polystyrene or polyurethane. Since, for various reasons, the boards have to be designed to be as light as possible, the actual plastic skin is not very thick.

U.S. Pat. No. 5,928,045 discloses a sports board having a foam core, and a deck layer, a bottom layer and an outer rail, which cover the foam core.

U.S. Pat. No. 3,337,886 discloses a surfboard having a core of foam material and an outer skin or shell.

GB 961,612 discloses surfboards composed of an expanded polystyrene plate with a plastic cover. The polystyrene material used for this surfboard is “water repellent”. The expanded polystyrene plate is covered with plastic. Although this combination provides a surfboard with water repellent characteristics and an external surface to support the users, the combination is not impact resistant.

EP 224 023 discloses a surfboard having a compound structure where the foaming core is covered with a synthetic resin and a thermoplastic material with a silver braid tissue sandwiched in-between. The silver braid tissue provides a more rigid foam structure.

FR 2 787 088 discloses a sandwich-type structure for a surfboard. This surfboard includes a soft foam core such as polystyrene and polyurethane between fiberglass and carbon. The structure is mounted with an adhesive substance such as epoxy resin and laminated polymers.

U.S. Pat. No. 5,275,860 discloses surf boards and body boards where the board includes a core foam which is a closed pore or closed cell foam to which is directly bonded an upper and lower skin. To achieve a substantially high integrity bond, an intermediate layer is composed of a mixture of the polymeric material of the foam and the different polymeric material of the skins. The foam is a polypropylene expanded bead foam while the skins are high density polyethylene.

U.S. Pat. No. 5,944,570 discloses a surfboard which has a prestressed center stringer with a foam core element located on each side of the stringer to form a center core element.

U.S. Pat. No. 4,798,549 discloses a surfboard that includes an elongated stringer with upper and lower surfaces curved generally to the longitudinal profile of the surfboard, a passage formed into and extending along the length of the stringer, outlet ports spaced along the stringer, a fin box formed in the stringer at the rear end thereof. The passage, ports, and fin box are constructed and arranged for the introduction of at least one of foam and steam therethrough for introduction into a space adjacent to said stringer.

U.S. Pat. No. 4,850,913 discloses a sports board for surfing, snow sledding, and other sports that has a shaped polyethylene foam core to which a polyethylene film/polyethylene foam sheet laminate is heat laminated over substantially all the surfaces of the core.

U.S. Pat. No. 4,887,986 discloses surfboards and sail boards that include an inflexible floating body having a stern and a prow; two flexible side portions attached to the inflexible floating body, one on either side thereof; and a mast foot located on the inflexible floating body, where the flexible side portions are incorporated into the flexible floating body from the stern to about the range of the mast foot and the inflexible floating body tapers between the flexible side portions in the direction of the stern to become a narrow bridge that is narrower than each of the flexible side portions.

U.S. Pat. No. 6,712,657 discloses body boards and surfboards having a spine member longitudinally mounted between the two halves of the board. Reinforcement members are mounted longitudinally and transversally along the board blanks.

U.S. Patent Application Publication 2006/0270288 discloses a process of wrapping a foam core surfboard shape with ¼″ slick foam skins via heat transfer. The heat transferred “foam stacked rail configurations” allow “pinstripes” to outline the outer edges of the board.

A body board is used by a rider to maneuver on ocean waves. The rider typically holds one or both side rails of the body board while the rider's hips, chest, knee, and/or foot are positioned on the top deck of the body board. The combination of ocean surf, the rider's weight, and the rider's directing the body board with the hands, elbows, torso, knee and/or foot places enormous flex and torsion stress on the body board. The flex and torsion stress tend to distort the body board, and generally this is an undesirable result because successful completion of maneuvers requires the body board's responding adequately to the rider's steering. Force applied to the body board that only distorts the board does not help the rider in redirecting the board. Thus, a high degree of stiffness of the body board is desirable.

On the other hand, simply making the body board to be very rigid is not a practicable solution because of weight concerns and because flex in the body board may be desirable along certain sections of the board. For example, it may be desirable for the board to be more flexible at a transverse line about a quarter of the way aft of the nose and lead corners. Such flexibility allows the rider to pull up the nose, distorting it above the plane of the main deck of the body board to keep the nose and lead corners from dropping under the water's surface in a dynamic situation where the nose is being forced downwardly. However, in the forward quarter of the board, it is generally considered desirable for the board to be very stiff along a transverse line so that the rider's steering inputs on one side of the board will effectively be transmitted to the opposite side of the board and redirect the opposite side. Notwithstanding these generalizations, variations in individual riders' styles and preferences for body board performance characteristics, as well as wide variations in surf conditions, complicate the task of providing appropriate stiffening to a body board.

In general, body boards can include a variable flexure characteristic, e.g., needed flexure in the nose area for what is known as “power turns” and strength in the mid and tail sections, which may be required for speed. The nose section can be configured to permit corner flexing or flexing along the entire nose section. In general, the bottom skin is smooth, tough and scratch resistant for speed over the water. The deck skin or upper surface of the board is textured to provide relative slip resistance.

In addition to the above, there is a characteristic of a body board known as “rocker”. This generally refers to the bending up from the centerline of the body board. There is overall rocker, nose rocker and tail rocker. Rocker usually affects the ability of the board to plane above the uneven surface of the water. There is no “perfect” rocker but there is general agreement on what constitutes a good rocker. Typically a good rocker involves a gentle curve upward from about ⅓ back from the nose with a resulting rise from the bottom of the board to about 1½ inches at the nose. The other ⅔ of the board should be flat or have a very small amount of rise from about ⅓ back from the nose.

Body boards are typically constructed of a buoyant foam core to which are attached an upper skin, a lower skin, and side rails. The added skins and rails provide durable outer surfaces, and the lower skin typically has a slick outer surface to speed the board on the water.

U.S. Patent Application Publication 2003/0008575 discloses a body board that includes a foam core with buoyancy to support a rider in water. A substantially solid and rigid, generally planar stiffening element is coupled to the core, for example by embedding therein, and the element provides a resistance to flexing in response to the rider's applying a bending force to the core. The stiffening element can include a beam oriented in a direction generally perpendicular to the longitudinal axis of the core, a beam oriented in a direction generally parallel to the longitudinal axis, and/or a beam oriented in a direction oblique to the longitudinal axis. The resistance to flexing provided by the stiffening element may increase in a continuously varying amount over at least a portion of the foam core. The element may provide the resistance along a first selected vector and a second selected vector, wherein the second selected vector is not parallel to the first.

A sled board is a sliding device that includes an elongate member configured to slide on any sufficiently downward sloping, slippery surface, such as snow, ice, grass, metal, or water on a water slide with one or more riders in a sitting, kneeling, or prone position.

U.S. Patent Application Publications 2003/0205872 and 2005/0035564 disclose a soft foam sled board prepared from a shaped polyethylene foam core, and at least the bottom surface of the core is covered by a slick, polyethylene film/polyethylene foam sheet laminate which provides little frictional resistance between the sled board and sliding surface.

A snow board is a sliding device that includes an elongate member configured to slide on a snow-covered downward sloping surface with one or more riders in a standing position.

U.S. Pat. No. 5,865,446 discloses a snow board that includes a first section having an upper surface, a lower surface, an outer end and an inner end, the outer end being upwardly curved to facilitate movement of the first section over a surface in a first direction; a second section having an upper surface, a lower surface, an outer end and an inner end, the outer end being upwardly curved to facilitate movement of the second section over the surface in a second direction; a flexible connector for connecting the inner end of the first section to the inner end of the second section, the flexible connector being capable of twisting and being flexible in both a horizontal and vertical direction; a first binding for securing one of the user's feet to the upper surface of the first section, the first binding being fixedly secured to the first section: and a second binding for securing the other foot of the user to the upper surface of the second section, the second binding being fixedly secured to the second section; whereby the user is able to facilitate the movement of the snow board in either the first or the second direction. The first and second sections of the snow board can each have a mid section positioned between the inner and outer ends and the mid-sections can be constructed from foam core or solid polymer resins.

A skateboard is a narrow elongated wheeled platform adapted for a rider to be transported in a standing position.

U.S. Pat. No. 5,716,562 discloses a method for making an injection molded, foamed, composite material skateboard. The skateboard body is formed of a composite material including a foamed structural plastic mass including plural, elongate strands of carbon fiber material distributed within the confines of the mass. The skateboard body is formed by injection molding using a thermoplastic such as nylon, polypropylene and polyethylene.

Sports boards that are lightweight are advantageous, as in most cases, it is desirable that the rider not have to carry any more weight than necessary. Additionally, in water applications, the weight of the board can adversely affect the buoyancy of the board.

Unfortunately, foam core boards utilizing polyurethane, expanded polystyrene, and/or expanded polypropylene tend to take on moisture when exposed to water making them heavier and less desirable.

Additionally, in many applications for sports boards, it is desirable for the board to have good flexibility, the ability of a board to “spring” back to its original shape when deformed. Flexibility can provide, for example, acceleration when surfing and improved turning radius and acceleration when snowboarding.

Though flexibility is a desirable attribute, it has proved elusive to build into a sports board, and typically requires time consuming and expensive construction methods.

Thus, there is a need in the art for sports boards that are light in weight, that do not take on water and that can provide good flexibility characteristics in an economical fashion.

SUMMARY OF THE INVENTION

The present invention provides a sports board that includes an elongate, water impervious, thermoplastic foam core having an upper surface and an under surface; an upper layer covering at least a portion of the upper surface; and an under layer covering at least a portion of the under surface. The foam core is made of a foamed material having a water absorption (measured according to ASTM C-272) of less than 2 volume percent volume percent.

The present invention also provides a surfboard that includes an elongate, water impervious, foam core comprising an interpenetrating network of one or more polyolefins and one or more polymers of vinyl aromatic monomers having and upper surface and an under surface; an upper layer covering at least a portion of the upper surface; and an under layer covering at least a portion of the under surface. The foam core is made of a foamed material having a water absorption (measured according to ASTM C-272) of less than 2 volume percent volume percent.

A surfboard blank that includes an elongate, water resistant, first portion comprising an expandable polymer matrix having an inner edge, a lead end and a tail end; an elongate, water resistant, second portion comprising an expandable polymer matrix having an inner edge, a lead end and a tail end; and a stringer disposed along and between the inner edges of the first portion and the second portion and secured thereto. The expandable polymer matrix contains one or more resins selected from interpolymers of a polyolefin and in situ polymerized vinyl aromatic monomers, rubber modified polystyrene, polyolefins, polystyrene modified rubber, polyphenylene oxide, and combinations and blends thereof.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top plan view of a surfboard according to embodiments of invention;

FIG. 2 shows a bottom plan view of a surfboard according to embodiments of the invention;

FIG. 3 shows a side elevation view of a surfboard according to embodiments of the invention;

FIG. 4 shows a cross sectional view of a surfboard according to embodiments of the invention;

FIG. 5 shows a cross sectional view of a surfboard according to embodiments of the invention;

FIG. 6 shows a top plan view of a surfboard according to embodiments of the invention;

FIG. 7 shows a bottom plan view of a surfboard according to embodiments of the invention;

FIG. 8 shows a side elevation view of a surfboard according to embodiments of the invention;

FIG. 9 shows a cross sectional view of a surfboard according to embodiments of the invention;

FIG. 10 shows a cross sectional view of a surfboard according to embodiments of the invention;

FIG. 11 is a top plan view of a body board according to embodiments of the invention;

FIG. 12 is a side elevation view of a body board according to embodiments of the invention;

FIG. 13 is a cross-sectional view of a body board according to embodiments of the invention;

FIG. 14 is a cross-sectional view of a body board according to embodiments of the invention;

FIG. 15 is a top plan view of a water ski according to embodiments of the invention;

FIG. 16 is a side elevation view of a water ski according to embodiments of the invention;

FIG. 17 is a cross-sectional view of a water ski according to embodiments of the invention;

FIG. 18 is a cross-sectional view of a water ski according to embodiments of the invention;

FIG. 19 is a top plan view of a snowboard according to embodiments of the invention;

FIG. 20 is a side elevation view of a snowboard according to embodiments of the invention;

FIG. 21 is a cross-sectional view of a snowboard according to embodiments of the invention;

FIG. 22 is a cross-sectional view of a snowboard according to embodiments of the invention;

FIG. 23 is a top plan view of a snow ski according to embodiments of the invention;

FIG. 24 is a side elevation view of a snow ski according to embodiments of the invention;

FIG. 25 is a cross-sectional view of a snow ski according to embodiments of the invention;

FIG. 26 is a cross-sectional view of a snow ski according to embodiments of the invention;

FIG. 27 is a top plan view of a sled according to embodiments of the invention;

FIG. 28 is a bottom plan view of a sled according to embodiments of the invention;

FIG. 29 is a side elevation view of a sled according to embodiments of the invention;

FIG. 30 is a cross-sectional view of a sled according to embodiments of the invention;

FIG. 31 is a top plan view of a surfboard blank according to embodiments of the invention;

FIG. 32 is a side elevation view of the surfboard blank of FIG. 31;

FIG. 33 is a top plan view of a surfboard blank according to embodiments of the invention;

FIG. 34 is a side elevation view of the surfboard blank of FIG. 33;

FIG. 35 is a top plan view of a surfboard blank according to embodiments of the invention; and

FIG. 36 is a side elevation view of the surfboard blank of FIG. 35.

DETAILED DESCRIPTION OF THE INVENTION

For the purpose of the description hereinafter, the terms “upper”, “lower”, “inner”, “outer”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, and derivatives thereof, shall relate to the invention as oriented in the drawing Figures. However, it is to be understood that the invention may assume alternate variations and step sequences except where expressly specified to the contrary. It is also to be understood that the specific devices and processes, illustrated in the attached drawings and described in the following specification, is an exemplary embodiment of the present invention. Hence, specific dimensions and other physical characteristics related to the embodiment disclosed herein are not to be considered as limiting the invention. In describing the embodiments of the present invention, reference will be made herein to the drawings in which like numerals refer to like features of the invention.

Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be understood as modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties, which the present invention desires to obtain. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10; that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations.

As used herein the term “surfboard” refers to an elongate member configured to float, which is suitable for one or more riders to use in a standing position to surf.

As used herein, the term “sailboard” refers to an elongate member configured to float, which is or can be fitted with a sail and is suitable for one or more riders to use in a standing position to windsurf and the like.

As used herein the term “body board” refers to an elongate member configured to float, which is used by a rider to maneuver on ocean waves in a sitting, kneeling or prone position.

As used herein the term “wave board” refers to a small roughly rectangular member configured to float, which is used by a rider to maneuver on ocean waves in a prone position.

As used herein the term “sled board” refers to a sliding device that includes an elongate member configured to slide on any sufficiently downward sloping slippery surface, such as snow, ice, grass, metal, or water on a water slide with one or more riders in a sitting, kneeling, or prone position.

As used herein the term “snow board” refers to a sliding device that includes an elongate member configured to slide on a snow-covered downward sloping surface with one or more riders in a standing position.

As used herein the term “skateboard” refers to a narrow elongated wheeled platform adapted for one or more riders to be transported in a standing position.

As used herein the term “snow ski” refers to a narrow, generally rectangular sliding device used in pairs to slide on a snow-covered downward sloping surface with a rider in a standing position with one foot secured to each device.

As used herein the term “water ski” refers to a narrow generally rectangular sliding device that can optionally be used in pairs, to glide along the surface of water while being pulled by a motorized water craft with a rider in a standing position with feet secured to one or two of such devices.

As used herein the term “go-kart” refers to a rectangular wheeled platform adapted for one or more riders to be transported in a sitting, kneeling, or prone position.

As used herein, the term “expandable polymer matrix” refers to a polymeric material in particulate or bead form that is impregnated with a blowing agent such that when the particulates and/or beads are exposed to heat, evaporation of the blowing agent (as described below) effects the formation of a cellular structure and/or an expanding cellular structure in the particulates and/or beads causing the bead to expand and when the expanded beads are placed in a mold and further exposed to heat, the beads can further expand and the outer surfaces of the particulates and/or beads can fuse together to form a continuous mass of polymeric material conforming to the shape of the mold.

As used herein, the terms “expanded plastics”, “prepuff”, “expanded resin beads” and “prefoam” refer to foamed thermoplastic particles that have been impregnated with a blowing agent, at least some of which has been subsequently removed (as a non-limiting example heated and expanded followed by evaporation and diffusion out of the bead) in a way that increases the volume of the particles and accordingly decreases their bulk density.

As used herein, the term “thermoplastic” refers to materials that are capable of softening, fusing, and/or modifying their shape when heated and of hardening again when cooled.

As used herein, the term “polymer” is meant to encompass, without limitation, homopolymers, copolymers and graft copolymers.

As used herein, the term “polyolefin” refers to a polymer prepared from at least one olefinic monomer, such as alpha unsaturated C₂-C₃₂ linear or branched alkenes, non-limiting examples of which include ethylene, propylene, 1-butene, 1-hexene and 1-octene.

As used herein, the term “polyethylene” refers to and includes not only a homopolymer of ethylene, but also an ethylene copolymer containing units of at least 50 mole %, in some cases at least 70 mole %, and in other cases at least 80 mole % of an ethylene unit and a corresponding proportion of units from a monomer copolymerizable with ethylene, and blends containing at least 50% by weight, in some cases at least 60% by weight, and in other cases at least 75% by weight of an ethylene homopolymer or copolymer with another polymer.

Non-limiting examples of monomers that can be copolymerized with ethylene include vinyl acetate, vinyl chloride, propylene, 1-butene, 1-hexene, 1-octene, and (meth)acrylic acid and its esters.

Polymers that can be blended with ethylene homopolymers or copolymers include any polymer compatible with ethylene homopolymers or copolymers. Non-limiting examples of polymers that can be blended with ethylene homopolymers or copolymers include polypropylene, polybutadiene, polyisoprene, polychloroprene, chlorinated polyethylene, polyvinyl chloride, styrene/butadiene copolymers, vinyl acetate/ethylene copolymers, styrenic polymers, acrylonitrile/butadiene copolymers, styrene/butadiene/acrylonitrile copolymers, and vinyl chloride/vinyl acetate copolymer.

As used herein, the term “styrenic polymers” refers to homopolymers of styrenic monomers and copolymers of styrenic monomers and another copolymerizable monomer, where the styrenic monomers make up at least 50 mole percent of the monomeric units in the copolymer. Non-limiting examples of styrenic monomers include styrene, p-methyl styrene, α-methyl styrene, tertiary butyl styrene, dimethyl styrene, dibromostyrene, nuclear brominated or chlorinated derivatives thereof and combinations thereof. Non-limiting examples of suitable copolymerizable monomers include 1,3-butadiene, C₁-C₃₂ linear, cyclic or branched alkyl (meth)acrylates (specific non-limiting examples include butyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate), butyl acrylate, acrylonitrile, vinyl acetate, alpha-methylethylene, divinyl benzene, maleic anhydride, maleic acid, fumaric acid, C₁-C₁₂ linear, branched or cyclic mono- and di-alkyl esters of maleic acid, C₁-C₁₂ linear, branched or cyclic mono- and di-alkyl esters of fumaric acid, itaconic acid, C₁-C₁₂ linear, branched or cyclic mono- and di-alkyl esters of itaconic acid, itaconic anhydride and combinations thereof.

As used herein, the terms “(meth)acrylic” and “(meth)acrylate” are meant to include both acrylic and methacrylic acid derivatives, such as the corresponding alkyl esters often referred to as acrylates and (meth)acrylates, which the term “(meth)acrylate” is meant to encompass.

As used herein, the term “molding” refers to the shaping of a pliable material to assume a new desired shape. Molding can involve the use of specific molding tools such as male and female molding tools, sculptured platens, and the like. It can also include the use of specifically shaped core members including compressible core members that are used to impart a desired shape to at least a portion of a thermoplastic material.

As used herein, the term “rubber” refers to natural or synthetic polymeric substances which have the ability to undergo deformation under the influence of a force and regain their original shape once the force is removed.

As used herein, the term “rubber modified polystyrene” refers to styrenic polymers where the styrenic polymer constitutes a continuous phase and the rubber constitutes a dispersed phase in the resin.

As used herein, the term “polystyrene modified rubber” refers to resins where the rubber constitutes a continuous phase and the styrenic polymer constitutes a dispersed phase in the resin as described in copending U.S. Patent Publication No. 2006-0276558 A1, the relevant portions of which are herein incorporated by reference.

The present invention provides a sports board that includes an elongate, water resistant or impervious, thermoplastic foam core having and upper surface and an under surface; an upper layer covering at least a portion of the upper surface; and an under layer covering at least a portion of the under surface.

The thermoplastic foam core contains a foamed expandable polymer matrix that is at least resistant or impervious to water. The expandable polymer matrix contains one or more thermoplastic resins. Suitable thermoplastic resins include, but are not limited to an interpolymers of a polyolefin and in situ polymerized vinyl aromatic monomers, rubber modified polystyrene, polystyrene modified rubber, polyphenylene oxide, blends of polyolefins and at least one other polymer, and combinations and blends thereof.

The thermoplastic resins can be in the form of beads, pellets, granules, or other particles convenient for use in expansion and molding operations.

In an embodiment of the invention, the thermoplastic resins indicated above can be blended with and can include one or more polymers selected from homopolymers of vinyl aromatic monomers; copolymers of at least one vinyl aromatic monomer with one or more of divinylbenzene, conjugated dienes, alkyl methacrylates, alkyl acrylates, acrylonitrile, and/or maleic anhydride; polyolefins; polycarbonates; polyesters; polyamides; natural rubbers; synthetic rubbers; and combinations thereof.

In an particular embodiment of the invention, the thermoplastic resins indicated above is a blend of one or more polyolefins and one or more polymers selected from homopolymers of vinyl aromatic monomers; copolymers of at least one vinyl aromatic monomer with one or more of divinylbenzene, conjugated dienes, alkyl methacrylates, alkyl acrylates, acrylonitrile, and/or maleic anhydride; polycarbonates; polyesters; polyamides; natural rubbers; synthetic rubbers; and combinations thereof.

In a particular aspects of this embodiment of the invention, the expandable thermoplastics can include thermoplastic homopolymers or copolymers selected from homopolymers derived from vinyl aromatic monomers including styrene, isopropylstyrene, alpha-methylstyrene, nuclear methylstyrenes, chlorostyrene, tert-butylstyrene, and the like, as well as copolymers prepared by the copolymerization of at least one vinyl aromatic monomer as described above with one or more other monomers, non-limiting examples being divinylbenzene, conjugated dienes (non-limiting examples being butadiene, isoprene, 1,3- and 2,4-hexadiene), alkyl methacrylates, alkyl acrylates, acrylonitrile, and maleic anhydride, wherein the vinyl aromatic monomer is present in at least 50% by weight of the copolymer. In an embodiment of the invention, styrenic polymers are used, particularly polystyrene. However, other suitable polymers can be included, such as polyolefins (e.g., polyethylene, polypropylene), polycarbonates, polyphenylene oxides, and mixtures thereof. In embodiments of the invention, mixtures of the above-mentioned polymers can be used.

As indicated above, the expandable polymer matrix can include an interpolymer of a polyolefin and in situ polymerized vinyl aromatic monomers and optionally other expandable polymers.

In embodiments of the invention, the interpolymer of a polyolefin and in situ polymerized vinyl aromatic monomers can be one or more of those described in U.S. Pat. Nos. 3,959,189; 4,168,353; 4,303,756, 4,303,757 and 6,908,949, the relevant portions of which are herein incorporated by reference. A non-limiting example of such interpolymers that can be used in the present invention include those available under the trade name ARCEL®, available from NOVA Chemicals Inc., Pittsburgh, Pa. and PIOCELAN®, available from Sekisui Plastics Co., Ltd., Tokyo, Japan.

In embodiments of the invention, the interpolymer of a polyolefin and in situ polymerized vinyl aromatic monomers is a particle or resin bead, which is subsequently processed to form the foam core of a sports board according to the present invention. The interpolymer particles used in the invention include a polyolefin and an in situ polymerized vinyl aromatic resin that form an interpenetrating network of polyolefin and vinyl aromatic resin particles. The interpolymer particles are impregnated with a blowing agent and optionally, a plasticizer.

Such interpolymer particles can be obtained by processes that include suspending polyolefin particles and vinyl aromatic monomer or monomer mixtures in an aqueous suspension and polymerizing the monomer or monomer mixtures inside the polyolefin particles. Non-limiting examples of such processes are disclosed in U.S. Pat. Nos. 3,959,189, 4,168,353 and 6,908,949.

In an embodiment of the invention, the polyolefin can include one or more polyethylene resins selected from low-, medium-, and high-density polyethylene; an ethylene vinyl acetate copolymer; an ethylene/propylene copolymer; a blend of polyethylene and polypropylene; a blend of polyethylene and an ethylene/vinyl acetate copolymer; and a blend of polyethylene and an ethylene/propylene copolymer. Ethylene-butyl acrylate copolymer and ethylene-methyl methacrylate copolymer can also be used.

As indicated above, the thermoplastic resin of the polymer matrix can include a polystyrene modified rubber where the rubber constitutes a continuous phase and the styrenic polymer constitutes a dispersed phase in the resin as described in copending U.S. Patent Publication No. 2006-0276558, the relevant portions of which are herein incorporated by reference.

In some embodiments of the invention, the expandable polymer matrix can include mixtures and combinations of the above-described thermoplastic resins. In other embodiments, the above-described thermoplastic resins or combinations of thermoplastic resins can be used in mixtures and combinations with other polymers. The mixtures and combinations can be used to provide particular properties to the expandable polymer matrix and/or foam core, such as water impermeability, flexural strength, elastic modulus, toughness, and/or tear strength.

In particular embodiments of the invention, the expandable polymer matrix can contain 100% interpolymers of a polyolefin and in situ polymerized vinyl aromatic monomers, but can also contain up to 99%, in some cases up to 95%, in other cases up to 90%, in some instances up to 80% and in other instances up to 75% based on the weight of the expandable polymer matrix of interpolymers of a polyolefin and in situ polymerized vinyl aromatic monomers. Also, the expandable polymer matrix can contain at least 25%, in some cases at least 30%, in other cases at least 40% and in some instances at least 50% based on the weight of the expandable polymer matrix of interpolymers of a polyolefin and in situ polymerized vinyl aromatic monomers. The amount of interpolymers of a polyolefin and in situ polymerized vinyl aromatic monomers in the expandable polymer matrix can be any value or range between any of the values recited above.

When other expandable polymers are included in the expandable polymer matrix with the interpolymers, the other expandable polymers can be present at a level of at least 1%, in some cases at least 5%, in other cases at least 10%, in some instances at least 20% and in other instances at least 25% based on the weight of the expandable polymer matrix. Also, the other expandable polymers can be present in the expandable polymer matrix at a level of up to 75%, in some cases up to 70%, in other cases up to 60% and in some instances up to 50% based on the weight of the expandable polymer matrix. The other expandable polymers can be included in the expandable polymer matrix at any level or range between any of the values recited above.

In other particular embodiments of the invention, the expandable polymer matrix can contain 100% polystyrene modified rubber, but can also contain up to 99%, in some cases up to 95%, in other cases up to 90%, in some instances up to 80% and in other instances up to 75% based on the weight of the expandable polymer matrix of polystyrene modified rubber. Also, the expandable polymer matrix can contain at least 25%, in some cases at least 30%, in other cases at least 40% and in some instances at least 50% based on the weight of the expandable polymer matrix of polystyrene modified rubber. The amount of polystyrene modified rubber in the expandable polymer matrix can be any value or range between any of the values recited above.

When other expandable polymers are included in the expandable polymer matrix with the polystyrene modified rubber, the other expandable polymers can be present at a level of at least 1%, in some cases at least 5%, in other cases at least 10%, in some instances at least 20% and in other instances at least 25% based on the weight of the expandable polymer matrix. Also, the other expandable polymers can be present in the expandable polymer matrix at a level of up to 75%, in some cases up to 70%, in other cases up to 60% and in some instances up to 50% based on the weight of the expandable polymer matrix. The other expandable polymers can be included in the expandable polymer matrix at any level or range between any of the values recited above.

In the present invention, the thermoplastic resins can be particles polymerized in a suspension process, which are essentially spherical resin beads useful for making expandable thermoplastic particles. However, polymers derived from solution and bulk polymerization techniques that are extruded and cut into particle sized resin bead sections can also be used.

In an embodiment of the invention, thermoplastic resin beads (unexpanded) containing any of resins, polymers and/or polymer compositions described herein can have a particle size of at least 0.2, in some situations at least 0.33, in some cases at least 0.35, in other cases at least 0.4, in some instances at least 0.45 and in other instances at least 0.5 mm. Also, the resin beads can have a particle size of up to 3, in some instances up to 2, in other instances up to 2.5, in some cases up to 2.25, in other cases up to 2, in some situations up to 1.5 and in other situations up to 1 mm. The resin beads used in this embodiment can be any value or can range between any of the values recited above.

The expanded impregnated thermoplastic resin beads can be expanded plastics, prepuff, and/or expanded resin beads as used in the present invention.

The expandable thermoplastic particles or resin beads can optionally be impregnated using any conventional method with a suitable blowing agent. As a non-limiting example, the impregnation can be achieved by adding the blowing agent to the aqueous suspension during the polymerization of the polymer, or alternatively by re-suspending the polymer particles in an aqueous medium and then incorporating the blowing agent as taught in U.S. Pat. No. 2,983,692. Any gaseous material or material which will produce gases on heating can be used as the blowing agent. Conventional blowing agents include aliphatic hydrocarbons containing 4 to 6 carbon atoms in the molecule, such as butanes, pentanes, hexanes, and the halogenated hydrocarbons, e.g., CFC's and HCFC's, which boil at a temperature below the softening point of the polymer chosen. Mixtures of these aliphatic hydrocarbon blowing agents can also be used.

Alternatively, water can be blended with these aliphatic hydrocarbons blowing agents or water can be used as the sole blowing agent as taught in U.S. Pat. Nos. 6,127,439; 6,160,027; and 6,242,540 in these patents, water-retaining agents are used. The weight percentage of water for use as the blowing agent can range from 1 to 20%. The texts of U.S. Pat. Nos. 6,127,439, 6,160,027 and 6,242,540 are incorporated herein by reference.

The impregnated thermoplastic resin beads are optionally expanded to a bulk density of at least 0.5 lb/ft³ (0.008 g/cc), in some cases, at least 1.25 lb/ft³ (0.02 g/cc), in other cases at least 1.5 lb/ft³ (0.024 g/cc), in some situations, at least 1.75 lb/ft³ (0.028 g/cc), in some circumstances, at least 2 lb/ft³ (0.032 g/cc) in other circumstances at least 3 lb/ft³ (0.048 g/cc), and in particular circumstances at least 3.25 lb/ft³ (0.052 g/cc) or 3.5 lb/ft³ (0.056 g/cc) thus forming pre-expanded thermoplastic beads or particles. When non-expanded resin beads are used, higher bulk density beads can be used. As such, the bulk density can be as high as 40 lb/ft³ (0.64 g/cc) and when only slightly expanded up to 30 lb/ft³ (0.48 g/cc), in some cases up to 20 lb/ft³ (0.32 g/cc), in other cases, up to 10 lb/ft³ (0.16 g/cc) and in some instances up to 7.5 lb/ft³ (0.12 g/cc). The bulk density of the thermoplastic particles can be any value or range between any of the values recited above.

The expansion step is conventionally carried out by heating the impregnated beads via any conventional heating medium, such as steam, hot air, hot water, or radiant heat. One generally accepted method for accomplishing the pre-expansion of impregnated thermoplastic particles is taught in U.S. Pat. No. 3,023,175.

The impregnated resin beads can be foamed cellular polymer particles as taught in U.S. Patent Publication No. 2002-0117769, the teachings of which are incorporated herein by reference. The foamed cellular particles can be any of the resins and/or polymers described above that can be expanded and contain a volatile blowing agent at a level of less than 14 wt %, in some situations less than 6 wt. %, in some cases ranging from about 2 wt. % to about 5 wt. %, and in other cases ranging from about 2.5 wt. % to about 3.5 wt. % based on the weight of the polymer.

When interpolymer resins are included in the expandable polymer matrix, the amount of polyolefin in the interpolymer resin of the invention can be at least 20%, in some cases at least 25%, and in other cases at least 30% and can be up to 80%, in some cases up to 70%, in other cases up to 60% and in some instances up to 55%, by weight based on the Weight of the interpolymer resin particles. The amount of polyolefin in the interpolymer resin can be any value or range between any of the values recited above.

The amount of polymerized vinyl aromatic resin in the interpolymer resin of the invention can be at least 20%, in some cases at least 30%, in other cases at least 40% and in some instances at least 45% and can be up to 80%, in some cases up to 75% and in other cases up to 70%, by weight based on the weight of the interpolymer resin particles. The amount of polymerized vinyl aromatic resin in the interpolymer resin can be any value or range between any of the values recited above.

The vinyl aromatic resin in the interpolymer resin can be made up of polymerized vinyl aromatic monomers or the resin can be a copolymer containing monomeric units from vinyl aromatic monomers and copolymerizable comonomers. Non-limiting examples of vinyl aromatic monomers that can be used in the invention include styrene, alpha-methylstyrene, ethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, vinylbenzene, and isopropylxylene. These monomers may be used either alone or in admixture.

Non-limiting examples of copolymerizable comonomers include 1,3-butadiene, C₁-C₃₂ linear, cyclic or branched alkyl (meth)acrylates (specific non-limiting examples include butyl (meth)acrylate, ethyl (meth)acrylate and 2-ethylhexyl (meth)acrylate), acrylonitrile, vinyl acetate, alpha-methylethylene, divinyl benzene, maleic anhydride, itaconic anhydride, dimethyl maleate and diethyl maleate.

Non-limiting examples of vinyl aromatic copolymers that can be used in the interpolymer resin of invention include those disclosed in U.S. Pat. No. 4,049,594. Specific non-limiting examples of suitable vinyl aromatic copolymers include copolymers containing repeat units from polymerizing styrene and repeat units from polymerizing one or monomers selected from 1,3-butadiene, C₁-C₃₂ linear, cyclic or branched alkyl (meth)acrylates (specific non-limiting examples including butyl (meth)acrylate, ethyl (meth)acrylate and 2-ethylhexyl (meth)acrylate), acrylonitrile, vinyl acetate, alpha-methylethylene, divinyl benzene, maleic anhydride, itaconic anhydride, dimethyl maleate and diethyl maleate.

In particular embodiments of the invention, the vinyl aromatic resin in the interpolymer resin includes polystyrene or styrene-butyl acrylate copolymers.

In embodiments of the invention, the interpolymer resin particles are formed as follows: The polyolefin particles are dispersed in an aqueous medium prepared by adding 0.01 to 5%, in some cases 2 to 3%, by weight based on the weight of the water of a suspending agent such as water soluble high molecular weight materials, e.g., polyvinyl alcohol or methyl cellulose or slightly water soluble inorganic materials, e.g., calcium phosphate or magnesium pyrophosphate and soap, such as sodium dodecyl benzene sulfonate, and the vinyl aromatic monomers are added to the suspension and polymerized inside the polyolefin particles.

Any conventionally known and commonly used suspending agents for polymerization of vinyl aromatic monomers can be employed. These agents are well known in the art and can be freely selected by one skilled in the art. Initially, the water is in an amount generally from 0.7 to 5, preferably 3 to 5 times that of the starting polyolefin particles employed in the aqueous suspension, on a weight basis, and gradually the ratio of the polymer particles to the water may reach around 1:1.

The polymerization of the vinyl aromatic monomers, which are absorbed in the polyolefin particles, is carried out using initiators.

The initiators suitable for suspension polymerization of the vinyl aromatic monomers are generally used in an amount of about 0.05 to 2 percent by weight, in some cases 0.1 to 1 percent by weight, based on the weight of the vinyl aromatic monomer. Non-limiting examples of suitable initiators include organic peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate and t-butyl perpivalate and azo compounds such as azobiisobutylonitrile and azobidimethylvaleronitrile.

These initiators can be used alone or two or more initiators can be used in combination. In many cases, the initiators are dissolved in the vinyl aromatic monomers, which are to be absorbed in the polyolefin particles. In other cases, the initiator can be dissolved in a solvent, such as toluene, benzene, and 1,2-dichloropropane.

When the in situ polymerization of the vinyl aromatic monomers is completed, the polymerized vinyl aromatic resin is uniformly dispersed inside the polyolefin particles.

In many cases, the polyolefin particles are cross-linked. The cross-linking can be accomplished simultaneously with the polymerization of the vinyl aromatic monomer in the polyolefin particles, and before impregnation of the blowing agent and/or plasticizer. For this purpose, cross-linking agents are used. Such cross-linking agents include, but are not limited to di-t-butyl-peroxide, t-butyl-cumylperoxide, dicumyl-peroxide, α,α-bis-(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di-(t-butylperoxy)-hexyne-3,2,5-dimethyl-2,5-di-(benzoylperoxy)-hexane and t-butyl-peroxyisopropyl-carbonate. These cross-linking agents are absorbed in the polyolefin particles together with the vinyl aromatic monomers by dissolving the cross-linking agent in an amount of about 0.1 to 2 weight % and in some cases 0.5 to 1 weight %, based on the weight of the polyolefin particles suspended in water. Further details of the cross-linking agents and the manner for absorbing the cross-linking agents into the polyolefin particles are provided in U.S. Pat. No. 3,959,189.

The interpolymer particles are acidified, dewatered, screened, and subsequently charged to a second reactor where the particles are impregnated with the blowing agent and/or plasticizer.

The impregnation step can be carried out by suspending the interpolymer particles in an aqueous medium, adding the blowing agent and/or plasticizer to the resulting suspension, and stirring at a temperature of, preferably, about 40° C. degrees to 80° C. The blowing agent and/or plasticizer can be blended together and then added to the interpolymer particles or can be added to the interpolymer particles separately.

Alternatively, the blowing agent and/or plasticizer can be added to the first reactor during or after the polymerization process.

The above processes describe a wet process for impregnation of the interpolymer particles. Alternatively, the interpolymer particles can be impregnated via an anhydrous process similar to that taught in Column 4, lines 20-36 of U.S. Pat. No. 4,429,059.

When polystyrene modified rubber resins are included in the expandable polymer matrix, these resins can be made by forming a dispersion of organic droplets by pressure atomizing an organic liquid mixture below the free surface of an aqueous phase, which can be stationary or flowing, or by applying mechanical agitation. The organic mixture typically contains an organic solution that includes one or more elastomeric polymers and/or one or more polyolefins dissolved in a monomer solution containing one or more styrenic monomers. The dispersed organic droplets typically have an average diameter of from about 0.001 mm to about 10 mm. The monomers are typically polymerized, using initiators as described above, in the dispersed organic droplets in a low shear flow pattern to form unexpanded polymer beads. In many cases, the organic mixture has a density of ±20% of the density of the aqueous phase and the dispersed organic droplets make up from 0.01 to 60 volume percent of the total volume of the organic and aqueous liquids.

In some embodiments, the low shear flow pattern is a controlled low turbulence flow pattern created, without mechanical agitation, by continuously or periodically injecting at gauge pressure up to 15 bar into selected parts of the reactor one or more streams of a gas inert to the reactor contents and immiscible with the reactor contents. The gas can be injected into the aqueous phase at a gauge pressure less than 3 bar and can form one or more streams of bubbles having diameters substantially larger than the average size of the atomized organic droplets.

In some embodiments, the low shear flow pattern is provided by mechanical agitation.

Typically, the unexpanded polystyrene modified rubber resin beads have a continuous phase and a dispersed phase and the continuous phase includes the elastomeric polymers and/or polyolefins in a crosslinked web morphology. The continuous phase can also include elastomeric polymers and/or polyolefins in a morphology that includes threads having a large aspect ratio, which are optionally at least partially crosslinked and/or connected via locally formed branches and/or an interconnected mesh structure.

In many embodiments, the organic mixture contains from about 5 to about 50 wt. %, based on the weight of the organic mixture, of one or more elastomeric polymers and/or one or more polyolefins and from about 95 to about 50 wt. % of a monomer solution that includes one or more styrenic monomers, where the elastomeric polymers and/or one or more polyolefins are soluble in the monomer solution.

In embodiments of the invention, the elastomeric polymers can be selected from homopolymers of butadiene or isoprene, and random, block, AB diblock, or ABA triblock copolymers of a conjugated diene with an aryl monomer and/or (meth)acrylonitrile and random, alternating or block copolymers of ethylene and vinyl acetate.

In some embodiments of the invention, the elastomeric polymers include one or more block copolymers selected from diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, ethylene-vinyl acetate, partially hydrogenated styrene-isoprene-styrene and combinations thereof. In other embodiments of the invention, the elastomeric polymers include one or more copolymers containing repeat units from the polymerization of one or more conjugated diene and at least one unsaturated nitrile selected from acrylonitrile and methacrylonitrile.

In an embodiment of the invention, the blowing agent can be dosed to the expandable polymer matrix in an extruder to produce resin pellets or beads. The extruder acts to mix the blowing agent into the expandable polymer matrix prior to extruding a strand of the mixture. The strand can be cut into bead or pellet lengths using an appropriate device, a non-limiting example being an underwater face cutter.

The particles and/or beads of the expandable polymer matrix according to the invention can also contain other additives known in the art, non-limiting examples including nucleating agents, anti-static additives; flame retardants; colorants or dyes; filler materials and combinations thereof. Other additives can also include chain transfer agents, non-limiting examples including C₂₋₁₅ alkyl mercaptans, such as n-dodecyl mercaptan, t-dodecyl mercaptan, t-butyl mercaptan and n-butyl mercaptan, and other agents such as pentaphenyl ethane and the dimer of alpha-methyl styrene. Other additives can further include nucleating agents, non-limiting examples including polyolefin waxes, i.e., polyethylene waxes.

The resulting expandable polymer matrix is used as a raw material in producing foam cores and/or blanks in the present sports boards. The blowing agent and/or plasticizers are introduced into the expandable polymer matrix resin particles to form foamable or expandable particles or resin beads, which in turn, are used to mold foam cores.

The blowing agent should have a boiling point lower than the softening point of the polyolefin and should be gaseous or liquid at room temperature (about 20 to 30° C.) and normal pressure (about atmospheric).

Blowing agents are well known in the art and generally have boiling points ranging from −42° C. to 80° C., more generally, from −10° C. to 36° C. Suitable hydrocarbon blowing agents include, but are not limited to aliphatic hydrocarbons such as n-propane, n-butane, iso-butane, n-pentane, iso-pentane, n-hexane, and neopentane, cycloaliphatic hydrocarbons such as cyclobutane and cyclopentane, and halogenated hydrocarbons such as methyl chloride, ethyl chloride, methylene chloride, trichlorofluoromethane, dichlorofluoromethane, dichlorodifluormethane, chlorodifluoromethane and dichlorotetrafluoroethane, etc. These blowing agents can be used alone or as mixtures. If n-butane, ethyl chloride, and dichlorotetrafluoroethane, which are gaseous at room temperature and normal pressure, are used as a mixture, it is possible to achieve foaming to a low bulk density. Specific types of volatile blowing agents are taught in U.S. Pat. No. 3,959,180. In particular embodiments of the invention, the blowing agent is selected from n-pentane, iso-pentane, neopentane, cylcopentane, and mixtures thereof.

The amount of the blowing agent ranges from about 1.5% to about 20% by weight, in some cases, about 1.5% to 15% by weight, and, in other cases, from 5% to 15% by weight, based on the weight of the expandable polymer matrix.

A plasticizer can be used in combination with the blowing agent and as stated herein above and acts as a blowing aid in the invention.

Suitable plasticizers include, but are not limited to benzene, toluene, limonene, linear, branched or cyclic C₅ to C₂₀ alkanes, white oil, linear, branched or cyclic C₁ to C₂₀ dialkylphthalates, styrene, oligomers of styrene, oligomers of (meth)acrylates having a glass transition temperature less than polystyrene, and combinations thereof.

In a particular embodiment of the invention, the plasticizer includes limonene, a mono-terpene hydrocarbon existing widely in the plant world. The known types are d-limonene, l-limonene, and dl-limonene. D-limonene is contained in the skin of citrus fruits and is used in food additives as a fragrant agent; its boiling point is about 176° C.; and its flammability is low. D-limonene is a colorless liquid, has a pleasant orange-like aroma, is approved as a food additive, and is widely used as a raw material of perfume. Limonene is not a hazardous air pollutant.

The amount of plasticizer can range from about 0.1 to 5 parts and in some cases from about 0.1 to about 1 part, by weight per 100 parts by weight of the expandable polymer matrix.

In many embodiments of the invention, the pre-expanded beads or particles containing the expandable polymer matrix are molded into a foam core shape of desired dimensions by adding pre-expanded particles or beads after four to 48 hours of ageing to completely fill a mold of the desired shape and dimensions and molding in a steam molding press. When steam is applied uniformly to the pre-expanded particles or beads, good fusion between beads is accomplished. When heat is also applied from the mold and/or mold press, a skin can be formed on the outer surface of the molded foam core.

The skin that is formed during molding provides a surface that readily accepts paint as well as laminating resins.

In prior art methods, the pre-expanded beads or particles are molded into a generally rectangular shape mold. The foam core is then prepared by cutting the general foam core shape into the block molded foam and then shaping the desired curvature to provide the foam core. This method is typically used in the prior art and results in any skin of the molded part being removed and the fused cell structure of the foam core being severely disrupted. This method results in significantly higher water absorption in the foam core as well as incompatibility with paint and laminating resins. The latter typically results in a non-uniform or wavy surface in the sports board, which is aesthetically undesirable and makes the sports board less aerodynamic.

In embodiments of the invention, these problems have been overcome by directly molding the foam core into its desired shape as described above to form a skin and/or by applying a sealant to the damaged surface created by cutting in the foam core shape.

Any sealant coating can be used that provides water repellant properties to the surface of the foam core and provides a surface that accepts laminating resins with little to no wrinkling or other surface deformation. Suitable sealants are formulations that include, but are not limited to, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers, styrene-butadiene polymers, styrene-isoprene polymers; styrene-butadiene-styrene block polymers; styrene-isoprene-styrene block polymers; and hydrogenated resins thereof and combinations thereof.

Other materials that can be used as or as part of the sealant, in some instances, include joint compound, gypsum paste, polyurethanes, styrenic block copolymers, polypropylene, and polyethylene.

In some embodiments, the sealant can be multilayered, including layers that contain any of the materials indicated above. Having one or more layers and the composition of those layers is determined based on the composition of the foam core and the composition of the upper layer covering and under layer covering. As a non-limiting example, sealant can include three components, a thermoplastic polyolefin; a thermoplastic styrenic polymer; and a styrenic block copolymer.

In some instances, the sealant includes film structures containing from 35 to 65 weight % of thermoplastic olefin, in some cases, from 55 to 60 weight %; from 10 to 30 weight % thermoplastic styrenic polymer, in some cases, from 15 to 20 weight %, with the balance being a styrenic block copolymer.

In particular instances, the sealant can include from 20 to 60 weight % polypropylene, in some cases, 40 to 50 weight %; from 20 to 60 weight % polystyrene, in some cases, from 40 to 50 weight %, with the balance being a styrenic block copolymer.

The styrenic block copolymer used in the sealant can be a copolymer of at least one vinyl aromatic monomer and at least one other olefin, diolefin and/or diene monomer. In particular embodiments, the styrene block copolymers can contain blocks of styrene and blocks of butadiene with from about 35 to 55 weight % bound styrene and a number average molecular weight (determined using gel permeation chromatography with polystyrene standards) of from about 50,000 to about 100,000. Non-limiting example of suitable styrenic block copolymers are those available under the trademark KRATON® from KRATON Polymers U.S. L.L.C. of Houston, Tex.

In some embodiments, the sealant includes multilayer structures that contain at least three layers, a thermoplastic polyolefin layer (TPO); a thermoplastic vinyl aromatic layer (TVA); and a tie layer (TL) which is located between the TLO layer and the TVA layer. This can be described as a TPO/TL/TVA structure. In some specific embodiments, the sealant can include film structures containing five layers, with the TVA layer being the core layer, as a non-limiting example, a five layer structure can be described as TPO/TL/TVA/TL/TPO.

When the sealant includes multilayer films, in many cases, the sealant contains about 5 to 25 weight % of tie layer material (based on the total weight of the multilayer structure). The tie layers can be used in amounts of from 5 to 10 weight % when preparing sheet structures, though it is possible to prepare useful structures, which contain less than 1% tie layer material. The amount of material used in the other layers can be widely varied to suit different end use. As a non-limiting example, a multilayer film containing similar amounts of polyolefin and thermoplastic styrenic polymer (e.g., from 10 to 20 weight % “tie layer” and 40-50 weight % in each of the TPO and TVA layers.

It is also within the scope of the invention to pre-mix the tie layer material with a part of the material used for one of the outer layers. This method can be used when only a very small weight % of the overall structure is contained in either the TPO layer of the TVA layer.

In embodiments of the invention, the foam cores described herein have a measured water absorption (measured according to ASTM C-272) of less than 2, in some cases, less than 1, and, in other cases, less than 0.5 volume percent determined on a sample molded to a density of from 1.5 to 2.5 lb/ft³ (0.024 to 0.04 g/cc).

In other embodiments of the invention, the foam cores described herein are made from materials that have a flexural strength at 5% strain (measured according to ASTM C-203) of at least 20 psi, in some cases, at least 25 psi and, in other cases, at least 30 psi at a molded density of about 1.5 lb/ft3 (0.024 g/cc); at least 30 psi, in some cases, at least 35 psi and, in other cases, at least 40 psi at a molded density of about 1.75 lb/ft3 (0.028 g/cc); at least 40 psi, in some cases, at least 45 psi and, in other cases, at least 50 psi at a molded density of about 2 lb/ft3 (0.032 g/cc); and at least 60 psi, in some cases, at least 65 psi and, in other cases, at least 70 psi at a molded density of about 2.25 lb/ft3 (0.036 g/cc).

In additional embodiments of the invention, the foam cores described herein are made from materials that have a tensile strength (measured according to ASTM D-3575-T) of at least 25 psi, in some cases, at least 30 psi and, in other cases, at least 35 psi at a molded density of about 1.5 lb/ft³ (0.024 g/cc); at least 40 psi, in some cases, at least 45 psi and, in other cases, at least 50 psi at a molded density of about 1.75 lb/ft³ (0.028 g/cc); at least 55 psi, in some cases, at least 60 psi and, in other cases, at least 65 psi at a molded density of about 2 lb/ft³ (0.032 g/cc); and at least 75 psi, in some cases, at least 80 psi and, in other cases, at least 85 psi at a molded density of about 2.25 lb/ft³ (0.036 g/cc).

In additional embodiments of the invention, the foam cores described herein are made from materials that have a foam tear strength (measured according to ASTM D-3575-G) of at least 5 lb/in, in some cases, at least 5.5 lb/in and, in other cases, at least 6 lb/in at a molded density of about 1.2 lb/ft³ (0.019 g/cc); at least 9 lb/in, in some cases, at least 10 lb/in and, in other cases, at least 11 lb/in at a molded density of about 1.5 lb/ft³ (0.024 g/cc); at least 12 lb/in, in some cases, at least 13 lb/in and, in other cases, at least 14 lb/in at a molded density of about 1.75 lb/ft³ (0.028 g/cc); at least 15 lb/in, in some cases, at least 17 lb/in and, in other cases, at least 18 lb/in at a molded density of about 2 lb/ft³ (0.032 g/cc); and at least 19 lb/in, in some cases, at least 20 lb/in and, in other cases, at least 22 lb/in at a molded density of about 2.25 lb/ft³ (0.036 g/cc).

Advantageously, the foam cores described herein have improved water repellant properties compared to expanded polystyrene foam cores in the prior art in that they absorb much less moisture and, therefore, do not take on undesirable weight when exposed to water.

Additionally, the foam cores described herein have higher tensile strength compared to expanded polyethylene or expanded polypropylene foam cores of the same density so the present foam cores are less likely to break during use.

Once the foam core has been made, an upper layer covering at least a portion of the upper surface of the foam core and an under layer covering at least a portion of the under surface of the foam core are applied.

In embodiments of the invention, upper layer covering and under layer covering include fibrous mats or fibrous fabric. The mats or fabric can be conventional and contain fibers such as glass fibers, aramide fibers, polyamide fibers, carbon fibers, silicon carbide fibers, composite fibers, metal fibers, fiberglass, and combinations thereof as well as fabric containing the above-mentioned fibers, and fabric containing combinations of the above-mentioned fibers.

When the prefabricated foam core has had one or more fibrous layers applied as the upper layer covering and/or under layer covering, a laminating resin is poured onto the fibrous mats at the upper and/or under surfaces of the foam core. The laminating resin can then be allowed to cure and harden, securing the fibrous layer(s) of the upper layer covering and/or under layer covering to the foam core.

In embodiments of the invention, after the laminating resin has been applied, the thus treated foam core or blank is inserted in a lower mold segment of a mold press in which the fibrous layer(s) with laminating resin is held by vacuum, and the mold press is closed. The pressure of the press causes the laminating resin to be completely distributed in the space between the foam core and the fibrous layer(s) and cures to form a closed fiber-reinforced shell, which comes into intimate connection with the foam core. The curing step can take place at a molding tool temperature of at least about 80° C. and for at least about 5 minutes.

After curing, the projecting film edges of the laminated foam core can be trimmed. Thereafter, the cut faces can optionally be sealed.

The laminating resin used to saturate the fibrous layer(s) is typically a resin system-catalyst component system that includes a resin system, a cure catalyst, and optionally filler materials.

In embodiments of the invention, the laminating resin can be a polyurethane formulation that includes a polyalcohol component and an isocyanate component; an epoxy formulation that includes an epoxy containing component and a reactive component such as a polyalcohol component; a curable polyester formulation that includes an unsaturated polyester resin component and a peroxide component, non-limiting examples of suitable peroxides include methyl ethyl ketone peroxide, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, t-butyl perpivalate di-t-butyl-peroxide, t-butyl-cumylperoxide, dicumyl-peroxide, α,α-bis-(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di-(t-butylperoxy)-hexane-3,2,5-dimethyl-2,5-di-(benzoylperoxy)-hexane and t-butyl-peroxyisopropyl-carbonate; a mixture of dimethyl phthalate and an ester plasticizer and methyl ethyl ketone peroxide second component; acrylic unsaturated polyester resins as disclosed in U.S. Pat. No. 5,395,866; epoxide-vinyl ester resins as disclosed in U.S. Pat. No. 4,595,734; and combinations thereof. The relevant portions of U.S. Pat. Nos. 5,395,866 and 4,595,734 are herein incorporated by reference.

In embodiments of the invention, the laminating resin system includes a curable unsaturated polyester resin and optionally a co-curable unsaturated monomer.

Curable unsaturated polyester resins are known in the art, and are generally prepared in a non-limiting sense, by esterification or transesterification of one or more unsaturated dicarboxylic acids or reactive derivatives thereof with one or more aliphatic or cycloaliphatic diols. Saturated dicarboxylic acids, aromatic dicarboxylic acids, or their reactive derivatives can be used in conjunction with the unsaturated dicarboxylic acid(s) to lower the crosslink density. Curable polyester resins are available commercially, and examples of such are disclosed in, as non-limiting examples, U.S. Pat. Nos. 3,969,560; 4,172,059; 4,491,642; 4,626,570, and 6,226,958 which are herein incorporated by reference.

The curable unsaturated polyester resins can be a high reactivity polyester resin. Non-limiting examples of suitable high reactivity polyester resins include, but are not limited to, high reactivity orthophthalic polyester resins, high reactivity isophthalic polyester resins, and high reactivity dicyclopentadiene-modified (DCPD) polyester resins. A particular non-limiting example of a curable unsaturated high reactivity polyester resin is a dicyclopentadiene-modified propylene glycol-maleate polyester resin.

Co-curable unsaturated monomers are also well known in the art, and include, as non-limiting examples, the various alkylacrylates and alkylmethacrylates as well as vinyltoluene .alpha.-methylstyrene, p-methylstyrene, and styrene. By the term “co-curing,” it is meant that the monomer contains reactive unsaturation capable of reacting with itself and/or the unsaturated sites of the curable polyesters under the curing conditions. Additional co-curable monomers are identified in the above-referenced patents. A non-limiting example of a co-curable monomer is styrene.

Non-limiting examples of suitable laminating resins include the SILMAR® and CoREZYN® products available from Interplastic Corporation, Saint Paul, Minn., the HI-POINT resins available from Crompton Corporation, Middlebury, Conn. and the polyester resins, a non-limiting example being Polyester Resin 30P-105, available from Dura Technologies, Inc., Bloomington, Calif.

Suitable fibrous layer fabric that can be used in the invention includes, but is not limited to, the above-described fibers in the following forms: plain weave, 14 mils thick cloth; plain weave, 11 mils thick cloth; plain weave, 10 mils thick cloth; plain weave, 8 mils thick cloth; plain weave, 5.5 mils thick cloth; four harness satin weave, 3.5 mils thick cloth; 2/2 twill weave, 9.3 mils thick cloth; modified plain weave, 7.7 mils thick cloth; eight harness satin weave, 8 mils thick cloth; eight harness satin weave, 9 mils thick cloth; and layers of combinations of such fabrics.

The sports boards utilizing the foam cores or blanks and methods of construction according to the invention provide boards that have a rapid “flex memory”, the ability of a board to very quickly “spring” back to its original shape when deformed. Flex memory can provide, for example, improved acceleration when surfing and improved turning radius and acceleration when snowboarding. Thus, flex memory is a desirable attribute that has proved elusive in prior art sports boards.

Sports boards constructed according to the invention can be evaluated using an Emerson 8510 compression tester, (Emerson Apparatus Company, Inc., Portland, Me.), designed in accordance with the requirements of ASTM D642 and TAPPI T804 equipment specifications. In these evaluations, a programmable platen is set at a rate of 0.5 inches (1.27 cm) per minute using a fixture of the type used in test protocols for alpine skis, a three point bending test as described in ASTM Standard 780-93a.

In this evaluation, the sports board is supported near each end by a 1.5″ diameter free floating steel rod so as to not apply any friction to the base of the board as it is being deflected from the top using a laminated structure that includes a rubber compliant fixture (19 inches long×1.5 inches wide) that follows the contour of the sports board deck so as to apply an equal amount of force across its width.

The amount of deflection that the sports boards according to the invention can withstand without breaking is greater than what is observed when compared to prior art sports boards.

Additionally, where prior art sports boards fail catastrophically are no longer capable of supporting a load, the sports boards constructed according the invention are able to continue to support a load even after failure. In other words, where prior art sports boards break, sports boards constructed according the invention bend and are tough enough to maintain some structural integrity.

An embodiment of the sports boards according to the invention is a surfboard as shown in FIGS. 1-4. Surfboard 10 has foam core elements 12 and 14 as described above separated by stringer 16 where foam core elements 12 and 14 are located on each side of stringer 16. Stringer 16 can be made of wood, carbon/graphite reinforced material, composite material, metal and/or combinations of such materials.

During manufacture, stringer 16 can be bowed in a gentle curve downward for its entire length to form a rocker shape from nose 18 to tail 20. Stringer 16 can be first formed with an upward curve from the approximate center to ends and relatively thicker structure in nose 18 half of stringer 16 relative to tail 20. Tail 20 half of stringer 16 is approximately straight at this step of the manufacture. Stringer 16 can then be further bowed downward under pressure in a stringer bending form to produce a gentle curve downward for approximately one half of its length from tail 20 to complete the overall rocker shape. Tail 20 end being relatively thinner bends in the bending form as compared to nose 18 end.

Thus a tail 20 with a top 22 concave and bottom 23 convex curved shape longitudinally is created. In addition, stringer 16 is thereby in a stress or spring condition with energy and tends to return to the original straight shape. Therefore, any force tending to bend tail 20 end upward must act against this spring force, thus providing a strong resistance to bending in an upward direction and a strong force to return to the original shape. Unique in the present invention is the added spring force supplied by the foam core acting to restore the surfboard to its original shape.

Upper layer covering 24 and under layer covering 26, as described more fully above are bonded to cover foam core elements 12 and 14 and stringer 16 to form outer layer 28 of surfboard 10. Outer layer 28 includes two components, a laminating resin with optionally added fillers and a fabric as described above.

Wood framed, metal or fiber reinforced epoxy framed fins 30 can be attached on bottom 23 near the tail 20.

The use of the present foam core elements 12 and 14 provides a flexible reinforced construction relative to nose 18 and tail 20 in that portion of surfboard 10. This, in combination with stringer 16, provides for flexure in the midsection of surfboard 10 which is torsional about stringer 16. Further, the density of foam core elements 12 and 14 can be higher at the nose 18 and tail 20 ends, and lower in the areas between to further provide flexure in the midsection of surfboard 10. Stated differently, the more foam core elements 12 and 14 allow nose 18 and tail 20 portions to tend to twist about stringer 16 when under pressure, or force of bending when used in surfing, in the water while nose 18 and tail 20 portions will tend to remain rigid, the greater the resulting spring back force will be. Optionally, in order to construct differences in flexure in surfboard 10, upper layer covering 24 and under layer covering 26 can be varied in stiffness by varying their respective thickness and/or composition. As a non-limiting example, nose 18 area can be relatively rigid, tail 20 area can be relatively rigid and the area in between can be relatively flexible.

This design provides for additional surfing or planning speed due to the spring and torsional action or rapid flex memory of tail 20 in the water. This feature provides for stability and ease of turning due to the relative flexibility and shape between the flexible area and the relatively rigid nose 18 and tail 20 ends of surfboard 10.

The embodiments shown in FIG. 4 utilize foam core elements 12 and 14 molded directly into their final shape, or molded nearly into the final shape and cut in half. As described above, directly molding the foam core to its final shape allows for a skin to form on the core elements that is not damaged by the laminating resin. FIG. 5 shows an embodiment of the invention where the foam core elements have been molded and then cut to their final shape. In this embodiment, the outer surfaces of foam core elements 12 and 14 and optionally stringer 16 are coated with sealant coating 32 prior to upper layer covering 24 and under layer covering 26 being affixed to foam core elements 12 and 14 and stringer 16.

An embodiment of the sports boards, according to the invention, is a surfboard as shown in FIGS. 6-9. Surfboard 110 has a foam core 112 as described above and a parabolic stringer 116 attached to the outer circumference of foam core 112. Parabolic stringer 116 can be made of wood, carbon/graphite reinforced material, composite material or metal.

In embodiments of the invention, parabolic stringer 116 can be made in two elements that are constructed such that the ends of each element accept and/or attach to each other. As a non-limiting example, at nose 118 and tail 120, the ends of each element of parabolic stringer 116 can be attached to each other.

During manufacture, parabolic stringer 116, or its individual elements, can be bowed in a gentle curve downward for its entire length to form a rocker shape from nose 118 to tail 120. Parabolic stringer 116 can be first formed with an upward curve from the approximate center to ends and relatively thicker structure in nose 118 half of parabolic stringer 116 relative to tail 120. Tail 120, half of parabolic stringer 116, or its elements is approximately straight at this step of the manufacture. Parabolic stringer 116, or its elements, can then be further bowed downward under pressure in a stringer bending form to produce a gentle curve downward for approximately one half of its length from tail 120, to complete the overall rocker shape. Tail 120 end being relatively thinner, bends in the bending form as compared to nose 118 end.

Thus a tail 120 with a top 122 concave and bottom 123 convex curved shape longitudinally is created. In addition, parabolic stringer 116 is thereby in a stress or spring condition with energy and tends to return to the original straight shape. Therefore, any force tending to bend tail 120 end upward must act against this spring force, thus providing a strong resistance to bending in an upward direction and a strong force to return to the original shape. Unique in the present invention is the added spring force supplied by foam core 112 acting to restore the surfboard to its original shape.

Upper layer covering 124 and under layer covering 126, as described more fully above, are bonded to cover foam 112 and parabolic stringer 116 to form outer layer 128 of surfboard 110. Outer layer 128 includes two components, a laminating resin with optionally added fillers and a fabric as described above.

Wood framed, metal or fiber reinforced epoxy framed fins 130 can be attached on bottom 123 near the tail 120.

In embodiments of the invention, the cross section of parabolic stringer 116 or its elements can have an inner surface 114 that is concave as shown in FIG. 9 or roughly perpendicular to top 122 and bottom 123 or straight as shown in FIG. 10.

The use of the present foam core 112 provides a flexible reinforced construction relative to nose 118 and tail 120 in that portion of surfboard 110. This, in combination with parabolic stringer 116, provides for flexure in the midsection of surfboard 110, which is torsional about parabolic stringer 116. Further, the density of foam core 112 can be higher at the nose 118 and tail 120 ends and lower in the areas between, to further provide flexure in the midsection of surfboard 110. Stated differently the more foam core 112 allows nose 118 and tail 120 portions to tend to twist in relation to parabolic stringer 116, when under pressure or force of bending, when used in surfing in the water while nose 118 and tail 120 portions will tend to remain rigid, the greater the resulting spring back force will be. Optionally, in order to construct differences in flexure in surfboard 110, upper layer covering 124 and under layer covering 126 can be varied in stiffness by varying their respective thickness and/or composition. As a non-limiting example, nose 118 area can be relatively rigid, tail 120 area can be relatively rigid and the area in between can be relatively flexible.

This design provides for additional surfing or planning speed due to the spring and torsional action or rapid flex memory of tail 120 in the water. This feature provides for stability and ease of turning due to the relative flexibility and shape between the flexible area and the relatively rigid nose 118 and tail 120 ends of surfboard 110. The present foam core and design allow surfers using surfboards according to the invention to traverse even the most gnarly waves.

The embodiments shown in FIG. 9 utilize foam core 112 molded directly into its final shape, or molded nearly into the final shape and parabolic stringer 116 either attached thereto or placed in a mold while foam core 112 is being molded. As described above, directly molding foam core 112 to its final shape allows for a skin to form on the foam core that is not damaged by the laminating resin. FIG. 10 shows an embodiment of the invention where the foam core has been molded and then cut to its final shape. In this embodiment, the outer surfaces of foam core 112 and optionally stringer 116 are coated with sealant coating 132 prior to upper layer covering 124 and under layer covering 126 being affixed to foam core 112 and stringer 116.

In embodiments of the present invention, the above-described surfboards include an elongate, water resistant or impervious, foam core containing an interpenetrating network of one or more polyolefins and one or more polymers of vinyl aromatic monomers having an upper surface and an under surface; an upper layer covering at least a portion of the upper surface; and an under layer covering at least a portion of the under surface, where the foam core is made of a foam material that has a water absorption (measured according to ASTM C-272) of less than 2 volume percent at a density of from 1.5 to 2.5 lb/ft³.

The surfboards according to the invention can be provided in any suitable length, such as big gun (9-foot or longer), longboard (8-10 feet long) or short board (less than 8 feet) lengths. When surfs up, the present surfboards provide a rider with the ability to takeoff and shoot the curl of the most mondo, cruncher or pounder wave in a quasimoto or other position and walk the board or perform shred, ripping, cut back, cut out, pull out and/or re-entry moves with ease. Most importantly, when using the present surfboards, a dude or dudette can catch a wave, get locked in and tubed, while screaming “banzai,” “cowabunga” or other appropriate expletives while enjoying a totally excellent gnarlatious ride.

FIG. 11 shows body board 210 configured to support a rider in water, has a generally elongate shape defining a longitudinal axis A, a nose end 212, and a tail end 214. An elongate foam core 216, as described above, provides the main bulk of body board 210, and foam core 216 is surrounded by an upper layer 218 and an under layer 220, as well as side layers 222 and 226 all bonded to core 216 as described above.

Upper layer 218, under layer 220 and side layers 222 and 226, as described more fully above, are bonded to cover foam core 216 and to form outer layer 228 of body board 210. Outer layer 228 includes two components, a laminating resin with optionally added fillers and a fabric as described above.

The use of the present foam core 216 provides a flexible reinforced construction relative to nose 212 and tail 214 in that portion of body board 210. This in combination with upper layer 218, under layer 220 and side layers 222 and 226 provides for flexure in the midsection of body board 210 which is torsional about longitudinal axis A. Further, the density of foam core 216 can be higher at the nose 212 and tail 214 ends and lower in the areas between to further provide flexure in the midsection of body board 210. Stated differently the more foam core 216 allows nose 212 and tail 214 portions to tend to twist in relation to longitudinal axis A, when under pressure, or force of bending when used in riding waves in the water while nose 212 and tail 214 portions will tend to remain rigid, the greater the resulting spring back force will be. Optionally, in order to construct differences in flexure in body board 210, upper layer 218, under layer 220 and side layers 222 and 226 can be varied in stiffness by varying their respective thickness and/or composition. As a non-limiting example, nose 212 area can be relatively rigid, tail 214 area can be relatively rigid and side layers 222 and 226 can be relatively flexible.

This design provides for additional planning speed due to the spring and torsional action or rapid flex memory of tail 214 in the water. This feature provides for stability and ease of turning. The present foam core and design allow surfers using surfboards according to the invention to traverse even the most gnarly waves.

The embodiments shown in FIG. 13 utilizes foam core 216 molded directly into its final shape, or molded nearly into the final shape. As described above, directly molding foam core 216 to its final shape allows for a skin to form on the foam core that is not damaged by the laminating resin. FIG. 14 shows an embodiment of the invention where the foam core has been molded and then cut to its final shape. In this embodiment, the outer surfaces of foam core 216 is coated with sealant coating 230 prior to upper layer 218, under layer 220 and side layers 222 and 226 being affixed to foam core 216.

Body boards according to the present invention are not distorted by flex and torsion stress and readily allow for successful completion of maneuvers by responding to the rider's steering. External forces do not tend to distort the present body board, making it easier for a rider to redirect the board. Thus, adequate and properly placed stiffness is provided in the present body board. Further, sufficient flex is also provided in the present body board, allowing the rider to pull up the nose, distorting it above the plane of the main deck of the body board to keep the nose and lead corners from dropping under the water's surface in a dynamic situation where the nose is being forced downwardly. Thus, flexibility for “power turns” and strength in the mid and tail sections for speed can readily be provided in the present body board.

FIG. 15 shows water ski 310 configured to support a rider in a standing position while being towed by a motorized watercraft on water, has a generally elongate shape defining a longitudinal axis A, a nose end 312, and a tail end 314. An elongate foam core 316, as described above, provides the main bulk of water ski 310, and foam core 316 is surrounded by an upper layer 318 and an under layer 320, as well as side layers 322 and 326 all bonded to core 316 as described above.

Upper layer 318, under layer 320 and side layers 322 and 326, as described more fully above, are bonded to cover foam core 316 and to form outer layer 328 of water ski 310. Outer layer 328 includes two components, a laminating resin with optionally added fillers and a fabric as described above.

Front foot insert 332 and back foot insert 334 can be attached to top 321 approximately midway between nose end 312 and tail end 314, or adjusted as desired. When two water skis 310 are used by a rider, each ski has front foot insert 332 and back foot insert 334 and the skier can insert a foot into each and ski conventionally. When slalom skiing is desired, second foot holder 336 can be attached to top 321 between back foot insert 334 and tail 314. Front foot insert 332, back foot insert 334, and second foot holder 336 can be constructed of a generally elastomeric material and attached to top 321 as is known in the art.

Wood framed or fiber reinforced epoxy framed fins 333 can be attached on bottom 323 near the tail 120.

The use of the present foam core 316 provides a flexible reinforced construction relative to nose 312 and tail 314 in that portion of water ski 310. This in combination with upper layer 318, under layer 320 and side layers 322 and 326 provides for flexure in the midsection of water ski 310 which is torsional about longitudinal axis A. Further, the density of foam core 316 can be higher at the nose 312 and tail 314 ends and lower in the areas between to further provide flexure in the midsection of water ski 310. Stated differently, the more foam core 316 allows nose 312 and tail 314 portions to tend to twist in relation to longitudinal axis A when under pressure or force of bending when used in water skiing while nose 312 and tail 314 portions will tend to remain rigid, the greater the resulting spring back force will be. Optionally, in order to construct differences in flexure in water ski 310, upper layer 318, under layer 320 and side layers 322 and 326 can be varied in stiffness by varying their respective thickness and/or composition. As a non-limiting example, nose 312 area can be relatively rigid, tail 314 area can be relatively rigid and side layers 322 and 326 can be relatively flexible.

This design provides for additional planning speed due to the spring and torsional action or rapid flex memory of tail 314 in the water. This feature provides for stability and ease of turning.

The embodiments shown in FIG. 17 utilizes foam core 316 molded directly into its final shape, or molded nearly into the final shape. As described above, directly molding foam core 316 to its final shape allows for a skin to form on the foam core that is not damaged by the laminating resin. FIG. 18 shows an embodiment of the invention where the foam core has been molded and then cut to its final shape. In this embodiment, the outer surfaces of foam core 316 are coated with sealant coating 330 prior to upper layer 318, under layer 320 and side layers 322 and 326 being affixed to foam core 316.

FIGS. 19 and 20 show snowboard assembly 410 that includes snowboard 412 to which a pair of bindings 414 are mounted to top side 416 snowboard 412. Bindings 414 can be conventionally mounted to a center portion snowboard 412.

FIG. 21 is a cross-section through snowboard 412 of FIGS. 19 and 20. Snowboard 412 includes foam core 418 completely surrounded by a skin 420 that includes upper layer 422, under layer 424 and side layers 426 and 428. Skin 420 as described more fully above is bonded to cover foam core 418 and includes two components, a laminating resin with optionally added fillers and a fabric as described above.

The density of foam core 418 can vary along the length of snowboard 412. As an example, the density of foam core 412 can be lower at tip portion 430 and tail portion 432 compared to mid portion 436.

The presently constructed snowboard assembly 410 has a mass moment of inertia, also called swing weight, that is reduced while maintaining a desired shear strength and compressive strength of the snowboard. The reduced swing weight permits snowboarders to more easily perform many maneuvers, especially turns.

In embodiments of the invention, the shear strength and crush (compression) strength of foam core 418 between top surface 416 and bottom surface 417 is sufficiently high to provide the desired swing weight.

In embodiments of the invention, the density of foam core 418 is no more than about 33% of the density of foam core 418 at mid portion 436.

The use of the present foam core 418 provides a flexible reinforced construction relative to tip portion 430 and tail portion 432 in that portion of snowboard 412. This, in combination with upper layer 422, under layer 424 and side layers 426 and 428 can provide for flexure in the midsection of snowboard 412 which can be torsional about longitudinal axis A. As a non-limiting example, the more foam core 418 allows tip portion 430 and tail portion 432 to twist in relation to longitudinal axis A when under pressure or force of bending when used in snowboarding while tip portion 430 and tail portion 432 will tend to remain rigid, the greater the resulting spring back force will be. Optionally, in order to construct differences in flexure in snowboard 412, upper layer 422, under layer 424 and side layers 426 and 428 can be varied in stiffness by varying their respective thickness and/or composition.

This design provides for stability and ease of turning.

The embodiments shown in FIG. 21 utilizes foam core 418 molded directly into its final shape, or molded nearly into the final shape. As described above, directly molding foam core 418 to its final shape allows for a skin to form on the foam core that is not damaged by the laminating resin. FIG. 22 shows an embodiment of the invention where foam core 418 has been molded and then cut to its final shape. In this embodiment, the outer surfaces of foam core 418 is coated with sealant coating 440 prior to upper layer 422, under layer 424 and side layers 426 and 428 being affixed to foam core 418.

FIGS. 23 and 24 show snow ski 500 according to the invention, having a front portion 510, an intermediate portion 508 and a rear portion 512. The ski is provided with a binding that includes a first portion 514 which is intended to co-act with the toe piece of a ski-boot and a second portion 516 which is intended to co-act with the heel of the boot.

FIG. 25 is a cross-section through snow ski 500 of FIGS. 23 and 24. Snow ski 500 includes foam core 520 completely surrounded by a skin 522 that includes upper layer 523, under layer 524 and side layers 526 and 528. Skin 522, as described more fully above, is bonded to cover foam core 520 and includes two components, a laminating resin with optionally added fillers and a fabric as described above.

The density of foam core 520 can vary along the length of snow ski 500. As an example, the density of foam core 520 can be lower at front portion 510 and rear portion 512 compared to intermediate portion 508.

The use of the present foam core 520 provides a flexible reinforced construction relative to front portion 510 and rear portion 512 in that portion of snow ski 500. This in combination with upper layer 523, under layer 524 and side layers 526 and 528 can provide for flexure in intermediate portion of snow ski 500. As a non-limiting example, the more foam core 520 allows front portion 510 and rear portion 512 to deflect when under pressure or force of bending when used in snow ski 500 while front portion 510 and rear portion 512 will tend to remain rigid, the greater the resulting spring back force will be. Optionally, in order to construct differences in flexure in snow ski 500, upper layer 523, under layer 524 and side layers 526 and 528 can be varied in stiffness by varying their respective thickness and/or composition.

This design provides for stability and ease of turning.

The embodiments shown in FIG. 25 utilizes foam core 520 molded directly into its final shape, or molded nearly into the final shape. As described above, directly molding foam core 520 to its final shape allows for a skin to form on the foam core that is not damaged by the laminating resin. FIG. 26 shows an embodiment of the invention where foam core 520 has been molded and then cut to its final shape. In this embodiment, the outer surfaces of foam core 520 is coated with sealant coating 540 prior to upper layer 523, under layer 524 and side layers 526 and 528 being affixed to foam core 520.

FIGS. 27-30 generally depict a sliding device, or sled according to the present invention. Sled 600 typically includes elongate member 602, configured to slide on any sufficiently slippery surface, such as snow, ice, grass, metal, or water on a water slide. Often, the surface is covered with snow or ice, and has a downward slope.

As illustrated in FIGS. 27-29, elongate member 602 includes a substantially flat, or planar, body portion 604, and a leading end portion 606. In use, a rider sits or kneels on body portion 604. Body portion 604 can include one or more handgrip(s) 608, posterior to leading end portion 606 and anterior to trailing edge 610. Leading end portion 606 has an inward end that is positioned to connect to or continuous with forward end of body portion 604. Leading end portion 606 typically extends outward from body portion 604 with an upturned shape, so as to avoid digging into the sliding surface when sled 600 moves forward.

Trailing edge 610 can be straight, can have a convex curve, or can have two or more convex curves, known in the art as bat tails.

FIG. 30 is a cross-section through sled 600 at elongate member 602. Sled 600 includes foam core 620 completely surrounded by a skin 622 that includes upper layer 623, under layer 624 and side layers 626 and 628. Skin 622 as described more fully above is bonded to cover foam core 620 and includes two components, a laminating resin with optionally added fillers and a fabric as described above.

The density of foam core 620 can vary along the length of sled 600. As an example, the density of foam core 620 can be lower at leading end portion 606 compared to body portion 604.

The use of the present foam core 620 provides a flexible reinforced construction relative to leading end portion 606 and body portion 604 in that portion of sled 600. This, in combination with upper layer 623, under layer 624 and side layers 626 and 628 can provide for flexure in sled 600. As a non-limiting example, the more foam core 620 allows leading end portion 606 to deflect when under pressure or force of bending when used in sled 600 while body portion 604 remains rigid, the greater the resulting spring back force will be. Optionally, in order to construct differences in flexure in sled 600, upper layer 623, under layer 624 and side layers 626 and 628 can be varied in stiffness by varying their respective thickness and/or composition.

This design provides for stability and ease of turning.

In FIG. 25 foam core 620 can be molded directly into its final shape, or molded nearly into the final shape. As described above, directly molding foam core 620 to its final shape allows for a skin to form on the foam core that is not damaged by the laminating resin. In an embodiment of the invention, foam core 620 can be molded and then cut to its final shape. In this embodiment, the outer surfaces of foam core 620 are coated with sealant coating 640 prior to upper layer 623, under layer 624 and side layers 626 and 628 being affixed to foam core 620.

One or more hand grip(s) or handles 608 can be affixed to sled 600 for a rider to grab onto during use. Often, sled 600 has a pair of handles 608 on opposite sides of sled 600.

As described above, a blank or foam core element that includes the above described foamed and molded expandable polymer matrix is a key component in the sports boards of the present invention. In various embodiments of the invention, the blank or foam core element can particularly be used to make surfboards.

FIGS. 31 and 32 show particular, non-limiting blank or foam core element embodiments for surfboards according to the invention. Blank 700 includes lead end 702, tail end 704, rocker portion 706, and stringer 708 extending from lead end 702 to tail end 704.

Lead end 702 is generally straight, perpendicular to and centered about stringer 708. Depending on the intended use and performance characteristics desired, lead end 702 can have a width 710 of from at least about 2, in some cases at least about 2.5, and in other cases at least about 3 inches and can be up to about 6, in some cases up to about 5 and in other cases up to about 4 inches. Width 710 can be any value or range between any of the values recited above.

Tail end 704 is generally straight, perpendicular to and centered about stringer 708. Depending on the intended use and performance characteristics desired, tail end 704 can have a width 712 of from at least about 3, in some cases at least about 4, and in other cases at least about 5 inches and can be up to about 12, in some cases up to about 10 and in other cases up to about 9 inches. Width 712 can be any value or range between any of the values recited above.

Depending on the intended use and performance characteristics desired, blank 700 can have a length 714 measured from lead end 710 to tail end 712 of from at least about 4, in some cases at least about 5, and in other cases at least about 6 feet and can be up to 10, in some cases up to about 9 and in other cases up to about 8 feet. Length 714 can be any value or range between any of the values recited above.

Rocker portion 706 of blank 700 generally curves upwards from a bottom surface of blank 700. Rocker portion 706 makes up the portion of blank 700 near lead end 702 and can be characterized in terms of what portion of length 714 curves upwardly to form rocker portion 706. The size of rocker portion 708 will vary depending on the intended use and performance characteristics desired in surfboards made from blank 700. Typically, rocker portion 706, can include at least the lead 10% of length 714, in some cases at least the lead 15% of length 714, and in other cases at least the lead 20% of length 714 and can be up to the lead 50% of length 714, in some cases up to the lead 40% of length 714, and in other cases up to the lead 30% of length 714. Rocker portion 706 of blank 700 can be any value or range between any of the values recited above.

Rocker portion 706 of blank 700 can be characterized by the amount the upward curve departs from the bottom surface of blank 700 (deflection 718). Deflection 718 represents the vertical distance from the plane of the bottom surface of blank 700 to lead end 702. The length of deflection 718 in rocker portion 708 will vary depending on the intended use and performance characteristics desired in surfboards made from blank 700. Deflection 718 can be at least about 3 inches, in some cases at least about 4 inches and in other cases at least about 4.5 inches and can be up to about 10 inches, in some cases at least about 8 inches, and in other cases at least about 6 inches. The length of deflection 718 can be any value or range between any of the values recited above.

Stringer 708 extends from tail end 704 to lead end 702 of blank 700 and is positioned between first portion 720 and second portion 722 of blank 700. Stringer 708 generally corresponds to the shape and curvature of blank 700, and in particular to rocker portion 706.

In many aspects of this embodiment, first portion 720 and second portion 722 are approximately equivalent in size, shape, weight and dimension. As indicated above, stringer 708 can be made of wood, carbon/graphite reinforced material, composite material, metal and/or combinations of such materials. Stringer 708 can be incorporated into blank 700 by cutting a molded plank of the expanded polymer matrix into two parts, first portion 720 and second portion 722, and subsequently using an appropriate adhesive to attaché first portion 720 and second portion 722 to opposing sides of stringer 708. Alternatively, expansion holes can be placed through stringer 718 and then be placed in a mold for molding blank 700 as described above. During the molding/bead expansion process, the expandable polymer matrix prepuff expands and fuses, in particular, expanding through the expansion holes to provide a one piece blank of first portion 720, stringer 708 and second portion 722.

The width and composition of stringer 708 are selected to provide desirable combinations of stiffness, response and flexibility. As such, the width of stringer 708, measured as the distance between first portion 720 and second portion 722, can be at least about 0.1 inches, in some cases at least about 0.2 inches and in other cases at least about 0.25 inches and can be up to about 2 inches, in some cases up to about 1.5 inches and in other cases up to about 1 inch. The width of stringer 708 can be any value or range between any of the values recited above.

FIGS. 33 and 34 show additional particular, non-limiting blank or foam core element embodiments for surfboards according to the invention. Blank 750 includes lead end 752, tail end 754, rocker portion 756, and stringer 758 extending from lead end 752 to tail end 754.

Lead end 752 is generally straight, perpendicular to and centered about stringer 758 and curves into the sides of blank 750. Depending on the intended use and performance characteristics desired, lead end 752 can have a width 760 of from at least about 1, in some cases at least about 1.5, and in other cases at least about 2 inches and can be up to about 5, in some cases up to about 4.5 and in other cases up to about 4 inches. Width 760 can be any value or range between any of the values recited above.

Tail end 754 is generally straight, perpendicular to and centered about stringer 758 and curves into the sides of blank 750. Depending on the intended use and performance characteristics desired, tail end 754 can have a width 762 of from at least about 4, in some cases at least about 5, and in other cases at least about 6 inches and can be up to about 14, in some cases up to about 12 and in other cases up to about 11 inches. Width 762 can be any value or range between any of the values recited above.

Depending on the intended use and performance characteristics desired, blank 750 can have a length 764 measured from lead end 752 to tail end 754 of from at least about 4, in some cases at least about 5, and in other cases at least about 6 feet and can be up to 10, in some cases up to about 9 and in other cases up to about 8 feet. Length 764 can be any value or range between any of the values recited above.

Rocker portion 756 of blank 750 generally curves upwards from a bottom surface of blank 750. Rocker portion 756 makes up the portion of blank 750 near lead end 752 and can be characterized in terms of what portion of length 764 curves upwardly to form rocker portion 756. The size of rocker portion 758 will vary depending on the intended use and performance characteristics desired in surfboards made from blank 750. Typically, rocker portion 756, can include at least the lead 10% of length 764, in some cases at least the lead 12.5% of length 764, and in other cases at least the lead 15% of length 764 and can be up to the lead 40% of length 764, in some cases up to the lead 30% of length 764, and in other cases up to the lead 25% of length 764. Rocker portion 756 of blank 750 can be any value or range between any of the values recited above.

Rocker portion 756 of blank 750 can be characterized by the amount the upward curve departs from the bottom surface of blank 750 (deflection 768). Deflection 768 represents the vertical distance from the plane of the bottom surface of blank 750 to lead end 752. The length of deflection 768 in rocker portion 758 will vary depending on the intended use and performance characteristics desired in surfboards made from blank 750. Deflection 768 can be at least about 2 inches, in some cases at least about 2.5 inches and in other cases at least about 3 inches and can be up to about 8 inches, in some cases at least about 7 inches, and in other cases at least about 6 inches. The length of deflection 768 can be any value or range between any of the values recited above.

Stringer 758 extends from tail end 754 to lead end 752 of blank 750 and is positioned between first portion 770 and second portion 772 of blank 750. Stringer 758 generally corresponds to the shape and curvature of blank 750, and in particular to rocker portion 756.

In many aspects of this embodiment, first portion 770 and second portion 772 are approximately equivalent in size, shape, weight and dimension.

Stringer 758 can be made of materials as described above, be dimensionally similar to and incorporated into blank 750 using the methods described in relation to blank 700.

FIGS. 35 and 36 show further particular, non-limiting blank or foam core element embodiments for surfboards according to the invention. Blank 800 includes lead end 802, tail end 804, rocker portion 806, and stringer 808 extending from lead end 802 to tail end 804.

Lead end 802 is generally straight, perpendicular to and centered about stringer 808 and curves into the sides of blank 800. Depending on the intended use and performance characteristics desired, lead end 802 can have a width 810 of from at least about 3, in some cases at least about 4, and in other cases at least about 5 inches and can be up to about 10, in some cases up to about 9 and in other cases up to about 8 inches. Width 810 can be any value or range between any of the values recited above.

Tail end 804 is generally straight, perpendicular to and centered about stringer 808 and curves into the sides of blank 800. Depending on the intended use and performance characteristics desired, tail end 804 can have a width 812 of from at least about 4, in some cases at least about 6, and in other cases at least about 8 inches and can be up to about 20, in some cases up to about 18 and in other cases up to about 16 inches. Width 812 can be any value or range between any of the values recited above.

Depending on the intended use and performance characteristics desired, blank 800 can have a length 814 measured from lead end 802 to tail end 804 of from at least about 4, in some cases at least about 5, and in other cases at least about 6 feet and can be up to 10, in some cases up to about 9 and in other cases up to about 8 feet. Length 814 can be any value or range between any of the values recited above.

Rocker portion 806 of blank 800 generally curves upwards from a bottom surface of blank 800. Rocker portion 806 makes up the portion of blank 800 near lead end 802 and can be characterized in terms of what portion of length 814 curves upwardly to form rocker portion 806. The size of rocker portion 808 will vary depending on the intended use and performance characteristics desired in surfboards made from blank 800. Typically, rocker portion 806, can include at least the lead 10% of length 814, in some cases at least the lead 12.5% of length 814, and in other cases at least the lead 15% of length 814 and can be up to the lead 40% of length 814, in some cases up to the lead 30% of length 814, and in other cases up to the lead 25% of length 814. Rocker portion 806 of blank 800 can be any value or range between any of the values recited above.

Rocker portion 806 of blank 800 can be characterized by the amount the upward curve departs from the bottom surface of blank 800 (deflection 818). Deflection 818 represents the vertical distance from the plane of the bottom surface of blank 800 to lead end 802. The length of deflection 818 in rocker portion 808 will vary depending on the intended use and performance characteristics desired in surfboards made from blank 800. Deflection 818 can be at least about 2 inches, in some cases at least about 2.5 inches and in other cases at least about 3 inches and can be up to about 9 inches, in some cases at least about 8 inches, and in other cases at least about 7 inches. The length of deflection 818 can be any value or range between any of the values recited above.

Stringer 808 extends from tail end 804 to lead end 802 of blank 800 and is positioned between first portion 820 and second portion 822 of blank 800. Stringer 808 generally corresponds to the shape and curvature of blank 800, and in particular to rocker portion 806.

In many aspects of this embodiment, first portion 820 and second portion 822 are approximately equivalent in size, shape, weight and dimension.

Stringer 808 can be made of materials as described above, be dimensionally similar to and incorporated into blank 800 using the methods described in relation to blank 700.

In embodiments of the invention, surfboards made according to the invention using the cores or blanks described in FIGS. 31-36 can be deflected using the Emerson 8510 compression tester apparatus as described 0.75 inches (1.9 cm), in some cases 0.79 inches (2 cm) and in particular instances 0.83 inches (2.1 cm) without demonstrating a deflection in the stress-strain curve. Additionally, the present surfboards do not fail when deflected 0.87 inches (2.2 cm), in some cases 0.91 inches (2.3 cm) and in particular instances 0.94 inches (2.4 cm). After such deflections, the present surfboards are able to return to their original shape. The particular properties of a particular board will depend on the composition of the blank or core and laminating resin used to glass the surfboard.

Further, even after failure of the present surfboards using the Emerson 8510 compression tester apparatus as described above, the present surfboards are able to support a load of at least 100 pounds (45.4 kg), in some cases at least 150 pounds (68 kg) and in other cases at least 200 pounds (91 kg). The particular properties of a particular board will depend on the composition of the blank or core and laminating resin used to glass the surfboard.

Because the sports boards of the present invention are made from the above-described expanded polymer matrix, they are generally lighter in weight than conventional sports boards, but can be handled in the same way because of the physical characteristics of the foam core and sports boards as described above. As such, the present sports boards are ideally suited for use in various sporting activities.

Various embodiments and structures have been described herein, which are not meant to be limiting to one application. Various designs and structures of one type of sports board can be incorporated into other types of sports boards to obtain desired characteristics as those skilled in the art will readily appreciate.

The present invention will further be described by reference to the following examples. The following examples are merely illustrative of the invention and are not intended to be limiting.

Example 1

This example demonstrates the superior flexibility of surfboards made according to the invention.

Test Apparatus

Testing was conducted on an Emerson 8510 compression tester, (Emerson Apparatus Company, Inc., Portland, Me.), designed in accordance with the requirements of ASTM D642 and TAPPI T804 equipment specifications. The programmable platen was set at a rate of 0.5 inches (1.27 cm) per minute. The fixture used was a modified design of the general test protocol for alpine skis, a three point bending test to ASTM Standard 780-93a.

Each surfboard was placed on the fixture, which was installed under the Emerson apparatus aligned to the same center point. The base of each surfboard was supported by a 1.5″ diameter free floating steel rod so as to not apply any friction to the base of the board as it was being deflected from the top. The spacing between the bottom rails is 28 inches and the selection of the spacing was determined through findings of the major compression points from the tail and lead end typically found while surfing.

The upper force fixture placed a downward force on the center of the surfboard as measured 38 inches form the lead end of the surfboard. The laminated structure included a rubber compliant fixture (19 inches long×1.5 inches wide) that followed the contour of the surfboard deck so as to apply an equal amount of force across the width of the surfboard.

Sample Description

The sample surfboards were similar to those shown in FIGS. 31 and 32, approximately 70 inches (178 cm) long. The blanks for each sample were molded, and cut in half lengthwise and a wooden stringer attached to each half with an adhesive. The blanks were glassed using a polyester laminate. All ingredients and construction were identical except for the foam material for the blanks, which were as follows:

-   -   Sample 1: 2.5 lb/ft³ (40 kg/m³) density polyurethane     -   Sample 2: 2.5 lb/ft³ (40 kg/m³) density expanded ARCEL® 730         resin (NOVA Chemicals Inc., Pittsburgh, Pa.)

Each surfboard was placed on the test apparatus and the platen was lowered until a break in the stress-strain curve indicated a failure. Sample 1 indicated a failure at 0.71 inches (1.8 cm) of deflection and sample 2 at 0.79 inches (2.0 cm) of deflection.

The performance of the foam crushing after the structural failure of each surfboard was evident in the formation of a downward trend in the stress-strain curve. The compressive set observed in samples 1 was much lower than that of sample 2, the foam in which appeared to store a degree of latent energy during compression.

The data demonstrate the superior flexibility of the surfboard made according to the invention.

Example 2

This example demonstrates the superior flexibility of surfboards made according to the invention. The test apparatus described in Example 1 was also used in this Example.

Sample Description

The sample surfboards were similar to those shown in FIGS. 31 and 32, approximately 70 inches (178 cm) long. The blanks for each sample were molded, and cut in half lengthwise and a wooden stringer attached to each half with an adhesive. The blanks were glassed using an epoxy laminate. All ingredients and construction were identical except for the foam material for the blanks, which were as follows:

-   -   Sample 3: 2.5 lb/ft³ (40 kg/m³) density expanded polystyrene     -   Sample 4: 2.5 lb/ft³ (40 kg/m³) density expanded ARCEL® 730         resin

Each surfboard was placed on the test apparatus and the platen was lowered until a break in the stress-strain curve indicated a failure. Sample 3 indicated a failure at 0.71 inches (1.8 cm) and sample 4 at 0.85 inches (2.2 cm) of deflection.

The performance of the foam crushing after the structural failure of each surfboard was evident in the formation of a downward trend in the stress-strain curve. The compressive set observed in samples 3 was much lower than that of sample 4, the foam in which appeared to store a degree of latent energy during compression.

The data demonstrate the superior flexibility of the surfboard made according to the invention.

Example 3

This example demonstrates the effect of laminate on the flexibility of surfboards made according to the invention. The test apparatus described in Example 1 was also used in this Example.

The sample surfboards were similar to those shown in FIGS. 31 and 32, approximately 70 inches (178 cm) long. The blanks for each sample were molded, and cut in half lengthwise and a wooden stringer attached to each half with an adhesive. The foam used for the blanks was 2.5 lb/ft³ (40 kg/m³) density expanded ARCEL® 730 resin. All ingredients and construction were identical except for the laminate resin used to glass the blanks, which were as follows:

-   -   Sample 5: blank glassed using an epoxy laminate     -   Sample 6: blank glassed using a polyester laminate

Each surfboard was placed on the test apparatus and the platen was lowered at a rate of 0.5 inches (1.27 cm) per minute to a deflection of 1 inch (2.54 cm). The deflection and load where a break in the stress-strain curve was noted as a deflection point. The deflection point for sample 5 was 0.85 inches (2.2 cm) at a load of 886 lb. (402 kg) and for sample 6 was 0.79 inches (2.0 cm) at a load of 728 lb. (330 kg).

The test above was repeated on the same boards, except the platen was lowered at a rate of 0.5 inches (1.27 cm) per minute to a deflection of 1.5 inches (3.8 cm). The deflection and load where a break in the stress-strain curve was again noted as a deflection point. The deflection point for sample 5 was 0.99 inches (2.5 cm) at a load of 687 lb. (312 kg) and for sample 6 was 0.95 inches (2.4 cm) at a load of 525 lb. (238 kg). Although both surfboards exhibited a deflection point, complete failure was not observed and the foam blank of each surfboard continued to support a load at the 1.5 inches (3.8 cm) deflection, 510 lb. (231 kg) for sample 5 and 490 lb. (222 kg) for sample 6.

A comparable test with the polyurethane surfboard of sample 1 demonstrated complete failure and no load support at 1.2 inches (3 cm) deflection. A comparable test with the expanded polystyrene surfboard of sample 3 demonstrated complete failure and no load support at 1.35 inches (3.4 cm) deflection.

A 2 inch (5 cm) diameter plug with a rounded top was engineered and fastened to a rigid base to support the plug. This fixture was attached with clamps to the upper moving platen of the Emerson compression tester. The face plate of the test fixture was driven downward at a rate of 0.5 inches (1.27 cm) per minute. The base of each surfboard was affixed to a solid steel table placed under the moving platen.

The outer skin of the sample 4 (epoxy laminate) provided a more durable shell demonstrating a peak load at 430 pounds (190 kg) with a peak deflection at 0.0456 inches (0.12 cm). Sample 5 demonstrated a peak load of 245 pounds (111 kg) at a crack deflection of 0.315 inches (0.8 cm).

The data demonstrate the toughness and durability properties of surfboards made according to the present invention and also highlight the improved safety features of such a board, as a safe degree of integrity is maintained even under conditions where prior art surfboards fail catastrophically.

The present invention has been described with reference to specific details of particular embodiments thereof. It is not intended that such details be regarded as limitations upon the scope of the invention except insofar as and to the extent that they are included in the accompanying claims. 

1. A surfboard comprising: (a) an elongate, water resistant, thermoplastic foam core having an upper surface and an under surface, a nose end, a tail end, and a stringer encased in the foam core extending from the nose end to the tail end; (b) an upper layer covering at least a portion of the upper surface; and (c) an under layer covering at least a portion of the under surface; wherein the foam core is made of a foam material 50 to 100 percent based on the weight of the foam material of expanded and fused interpolymer resin particles containing from about 20% to about 80% by weight of a polyolefin and from about 80% to about 20% by weight; wherein the density of the foam core is from about 0.02 g/cc to about 0.64 g/cc and the density of the foam core is higher at the nose end and tail end as compared with the rest of the foam core; wherein the foam core comprises a skin, consisting of the foam material, formed on the upper surface and under surface; wherein the foam core has a water absorption (measured according to ASTM C-272) of less than 2 volume percent wherein the upper layer and under layer comprise a cloth comprising a fiber selected from the group consisting of carbon fibers, graphite fibers, aramid fibers, metal fibers, glass fibers, silicon carbide fibers, polyester fibers, composite fibers, and fiberglass; and wherein the cloth is encased in a laminating resin, which forms a bond to the thermoplastic foam core. 2-4. (canceled)
 5. The surfboard according to claim 1, wherein a sealant is applied to at least a portion of the outer surface or under surface of the foam core.
 6. The surfboard according to claim 5, wherein the sealant comprises a material selected from the group consisting of ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers, styrene-butadiene polymers, styrene-isoprene polymers; styrene-butadiene-styrene block polymers; styrene-isoprene-styrene block polymers; and hydrogenated resins thereof.
 7. The surfboard according to claim 1, wherein the foam core has a flexural strength at 5% strain, measured according to ASTM C-203, of at least 60 psi at a molded density of about 2.25 lb/ft³.
 8. The surfboard according to claim 1, wherein the foam core has a tensile strength (measured according to ASTM D-3575-T) of at least 75 psi at a molded density of about 2.25 lb/ft³. 9-10. (canceled)
 11. The surfboard according to claim 1, wherein the laminating resin comprises a resin selected from the group consisting of unsaturated polyester resins, saturated polyester resins, epoxy resins, phenol-formaldehyde resins, melamine-formaldehyde resins, urea-formaldehyde resins, unsaturated polyesteramide resins, vinyl ester resins, polyimide resins, poly amide-imide resins, unsaturated (meth)acrylic resins, acrylic-urethane resins, and combinations thereof.
 12. The surfboard according to claim 1, wherein the upper layer covering and/or under layer covering comprise one or more polyolefins. 13-25. (canceled)
 26. The surfboard according to claim 1, wherein the stringer is an axial or a parabolic stringer.
 27. The surfboard according to claim 1, comprising one or more fins secured to and extending from the under surface of the surfboard.
 28. The surfboard according to claim 1, wherein the surfboard can be deflected 0.75 inches (1.9 cm) without demonstrating a deflection in the stress-strain curve.
 29. The surfboard according to claim 1, wherein the surfboard does not fail when deflected 0.87 inches (2.2 cm).
 30. A sports board comprising (a) an elongate, water resistant, thermoplastic foam core having an upper surface, an under surface, a nose end and a tail end; (b) an upper layer covering at least a portion of the upper surface; and (c) an under layer covering at least a portion of the under surface; wherein the foam core is made of a foam material comprising 50 to 100 percent based on the weight of the foam material of expanded and fused interpolymer resin particles containing from about 20% to about 80% by weight of a polyolefin and from about 80% to about 20% by weight; wherein the density of the foam core is from about 0.02 g/cc to about 0.64 g/cc and the density of the foam core is higher at the nose end and tail end as compared with the rest of the foam core; wherein the foam core comprises a skin, consisting of the foam material, formed on the upper surface and under surface; wherein the foam core has a water absorption of less than 2 volume percent measured according to ASTM C-272; wherein the upper layer and under layer comprise a cloth comprising a fiber selected from the group consisting of carbon fibers, graphite fibers, aramid fibers, metal fibers, glass fibers, silicon carbide fibers, polyester fibers, composite fibers, and fiberglass; and wherein the cloth is encased in a laminating resin, which forms a bond to the thermoplastic foam core.
 31. The sports board according to claim 30, wherein the sports board is selected from the group consisting of a surfboard, a body board, a sailboard, a wave board, a tow board, a water ski, a snow board, a sled, a toboggan, and a snow ski. 